Apple has just seeded developers of iPhone’s Developer program with a second beta version of iPhone SDK 2.1. As seen in the release notes below, it appears that the new version fixes several bugs in iPhone firmware.
"This is the second beta of the iPhone SDK targeting iPhone OS 2.1,
including bug fixes to iPhone OS as well as an early implementation of
the Apple Push Notification Service API. This API is not yet integrated
with a live push server."
Apple had released the first beta version of iPhone firmware 2.1 only last week which hinted of the
much-awaited Copy & Paste and Turn-by-Turn GPS feature.