The file is called: iPhone1,2_2.0_5A347_Restore.ipsw and you can snag it from apple here http://appldnld.apple.com.edgesuite....7_Restore.ipsw
keep in mind this is only for the iphone. Ipod touch users will have to wait a little bit longer today. Also when you go to put it on your phone, for windows users hold the shift key when you click restore so you can tell it to use the file downloaded.
Use it at your own risk, and keep in mind if you have an unlocked phone, this will lock it, so dont install it. Your phone wont be jailbroken either.
If you do update your phone, you can install apps now. Super monkey ball rocks, and the ebay app is very nice
The 2.0 firmware erases every bit of data and info on your iPhone and completely installs the iPhone 2.0 firmware. So as long as you are on AT&T, you can officially use all features available on the phone.
Your phone obviously WONT be unlocked, NOT would it be jailbroken.