Firmware update 2.2.1 (5H11a) for iPhone and iPod Touch is now available from Apple via iTunes. Besides some bug fixes, 2.2.1 also includes a baseband update, which brings the modem firmware to version 02.30.03. The iPhone Dev-Team immediately suggested that users with jailbroken and/or unlocked devices wait for further instructions while they continue to inspect the update.
Apple announced that this latest update improves the stability of MobileSafari. The firmware also fixes an issue where images saved from Mail sometimes display improperly in the camera roll. The iPod Touch update includes a fix to prevent Apple Lossless Audio Codec files (ALAC) from skipping during playback.
The update is compatible with all generations of both the iPhone and iPod Touch. As always, users interested in updating can click "check for updates" in iTunes to download and install the 246MB file from Apple.
The Dev-Team has already stated that 2.2.1 looks like it will break yellowsn0w. They will surely report back as soon as they know more details, and release a custom firmware update that preserves the baseband if necessary. Again, if your device is jailbroken and/or unlocked, or you intend to jailbreak the phone in the near future, DO NOT install the 2.2.1 update until further notice!