Sure, you already know about cut-and-paste, picture messaging (one AT&T gets around to supporting it, that is) and "Find My iPhone"—but have you heard about the "shake to undo" feature, auto-fill for Safari, and the new way to quit from a frozen app? Get the scoop right here.

We've had iPhone Software 3.0 for almost a day now (there's also a version for the iPod Touch, although it'll cost you $9.95 to download), and all the big new features have been thoroughly poked and prodded by now. Meanwhile, some of the most sought-after features—such as MMS, a.k.a. picture message—and laptop tethering have yet to be supported by AT&T (later this summer, we've been told).

So instead of simply rehashing such features as universal Spotlight search and voice memos (really, Apple, what took you so long?), I've compiled a list of my favorite little features in Software 3.0—along with a couple of bigger ones that I find particularly enticing.

The list isn't meant to be comprehensive—these are just the tips and tricks that I've found most useful so far. Have some that you'd like to share? Then by all means, post them in the comments below for all to see. (For a complete list of new 3.0 features, such as copy-and-paste and universal search, check out Apple's Web site, along with some of my earlier posts here and here.)

And without further ado, here we go…

Call a number directly from a calendar entry
Now, here's an IPhone feature I've really been longing for. If you have an address or phone number in the "Notes" field of a calendar entry, you can now tap them to either map the address or call the number. And if the address and/or phone number isn't getting hotlinked properly, you can always just copy and paste.

Force quit a frozen app
Now you don't have to do a hard reset on your iPhone (performed by pressing and holding the Sleep and Home buttons) if a third-party app goes haywire. Instead, you can just kill the errant process in a couple simple steps. First, press and hold Sleep and Home as if you're doing a hard reset; next, press and hold the Home button. Within a few seconds, you'll be back at the Home screen.

Shake to shuffle or undo
Again, nothing new (especially for owners of some of the newer Sony Ericsson music phones), but cool nonetheless. Listening to a playlist and want to change things up? Just give your iPhone a quick shake; you'll hear a little "beep-bap-boop" sound, and you'll be in shuffle mode. Also: Not thrilled with the sentence you just typed? Shake the phone, and a pop-up will appear, asking whether you'd like to undo your typing.

Log into your YouTube account
Yep, other smartphones have been able to do this for a long time now, but better late than never. Just More and then My Videos or Subscriptions, and you'll be prompted for your YouTube username and password; once that's done, you'll be able to access your clips and subscriptions (natch), rate or comment on videos, subscribe to new channels, and so on.

Compose an email, a text message, or a note with landscape keypad
One of the biggest complaints about the iPhone has finally been fixed—yes, you can now tap on a landscape version of the iPhone's touch keypad from just about any app. Simply turn your handset on its side whenever you're tapping out a new e-mail, SMS, or a sticky, and the landscape keypad will appear.

Auto-fill your info
Shopping on the iPhone just got a lot easier with this 3.0 feature. Tap Settings, Safari, and AutoFill; then, if you want iPhone to automatically fill in Web forms with your contact info, switch the On/Off slider to On and select your own contact card from the address book. You can also set Safari to remember usernames and passwords if you with.

Rent a movie or buy a TV show over Wi-Fi
OK—not exactly a "hidden gem" as 3.0 features go, but as a movie freak I can't resist. At last, you can directly download movie rentals, purchases, or TV episodes over the air; just click on the iTunes app to get started. The bad news is that AT&T's 10MB cap on iTunes downloads over its 3G network still applies, which basically means you'll need Wi-Fi access to grab a 1GB movie rental at the airport. The good news, though, is that all iPhone users get free access to AT&T hotspots, including those at Starbucks—which, as luck would have it, are easy to find at airports. Plan on sipping that latte slowly, however; even over my speedy Wi-Fi connection, it took a good half hour to download a 1.2GB movie like Robert Rodriguez's "Planet Terror." (And yes, you can transfer movie rentals back to your Mac/PC if you wish.)

Keep a closer eye on the market
The iPhone's (Yahoo!-powered) Stocks app gets a bit more useful in Software 3.0. When you tap on a specific ticker symbol, you'll still see the daily, month, or yearly price chart on the bottom half of the screen; now, though, you can swipe it for recent headlines or volume, market cap, 52-week high and low info, and more.

Forward or delete a text message
I've always liked how the iPhone displays SMS conversations in a "threaded" format, but until now, there wasn't a way to forward pithy texts or delete specific messages (besides simply wiping an entire conversation). Now, you can; just tap Edit in an SMS conversation, then select the messages you'd like to forward or zap.

Get "push" notifications
Again, probably not the most "hidden" feature in 3.0, but I like it so much that I'm including it anyway. The iPhone still lacks true multitasking (as found on the Palm Pre), but with "push notification"—new to Software 3.0—developers of third-party apps can "push" alerts, sounds, and icon badges to your phone even when the given app isn't running. For example, the Associated Press app will push you a pop-up window with a sound alert when a bulletin hits the wire (I just got one for a Supreme Court ruling on DNA testing), while Tap Tap Revenge will ping you whenever one of your Tap Tap pals wants to challenge you to an over-the-air duel. (MacRumors has a list of early push-supported apps here.) Don't worry—you can configure push notification in the Settings menu, or turn it off entirely if you wish. (Also, keep in mind that turning push notification on may put a dent in your battery life.)

What are your favorite new feature in iPhone Software 3.0? Post 'em below.