iPhone 2.1 Beta 1: GPS Boost + Notification Server APIs
Apple has reportedly seeded an early beta of firmware 2.1 (5f90) and a new and improved SDK to developers. Among the changes, CoreLocation (which covers GPS and other location-aware services) gains direction and speed tracking abilities (leading to a fresh round of turn-by-turn speculation, 'natch), and API's for the Notification Server that, come September, will be used in-lieu of background multitasking to push alert badges and sounds to Apps (like Instant Messages, Tweets, etc.). Given how MobileMe is doing with Push, that one may prove interesting...
On the negative side, 2.1 is one way street. Developers using 2.1 can not create binaries compatible with the current 2.0-centric App Store, so they either have to maintain two independant development environments (Update: possibly 3 environments and up to 6 devices, 2.0 and 2.1 for iPhone 3G (with mandatory carrier plans), iPhone 2G, and iPod Touch -- expensive much?), or wait for App Store 2.1 to launch (in September along with Notification Server?)
Of course, before 2.1 we'll likely see the already being tested 2.0.1, which will hopefully fix many of the bugs plaguing upgraders and new adopters both. Like, really soon, right Apple?