As promised, Apple releases iPhone Software 2.1 today. The update is available through iTunes 8.

iPhone OS 2.1 for iPod touch and iPhone is available through iTunes (installation of iTunes 8 is required).

iPhone Software 2.1 for iPhone – iPhone1,1_2.1_5F136_Restore.ipsw 231MB
iPhone Software 2.1 for iPhone 3G – iPhone1,2_2.1_5F136_Restore.ipsw 237.8MB
iPhone Software 2.1 for iPod touch – iPod1,1_2.1_5F137_Restore.ipsw 239.5MB

Before you upgrade to iPhone Software 2.1, you might want to do the followings:

• Import all the pictures from the iPhone.
• Import all the purchased songs, movies, and apps if necessary.
• Sync your iPhone with your computer using iTunes 8.
• Let iTunes perform complete back-up of your phone.

If your iPhone is having trouble doing any of the above, it might indicate problems with your current iPhone. Please proceed with caution.

Security Updates included in iPhone Software 2.1 release notes can be found here.