According to numerous accounts Apple has released the Beta 1 of the iPhone 2.2 firmware to developers for testing. The new version is accompanied by a beta for the new iPhone SDK (build 9M2611). It is still unclear what the new firmware will offer. The last firmware update (2.1) provided several improvements to features that iPhone users were unhappy with, but there is no word yet on what 2.2 might present.
Widespread speculation concerns Apple's once promised background push notification, which would allow users to receive IM's while browsing the web or being on their email program. But, since Steve Jobs himself notes that this feature is "running a bit late," there is no telling what 2.2 Firmwaire will entail.