Apple released a new beta version of the iPhone SDK today. So what changed from the last beta, you ask? It’s a little hard to tell from the links Apple provides on their developer website because the link to the API diffs (iPhone developer account required) always lists all changes from the most recent stable version. So if you have already downloaded beta 1 and beta 2, you are now reading the same document for the third time.
Thankfully, Apple also provides a documents that only lists the changes from the last beta version, but it is not listed on the developer home page: /prerelease/library/releasenotes/General/iPhoneSeedAPIDiffs/index.html
(iPhone developer account required)
This URL seems to remain constant between beta releases. In other words, it always lists the differences between the most recent beta release and its predecessor. If you follow the SDK betas it’s a good idea to bookmark that page.