Apple has released another beta of iPhone OS 3.0. This third beta has relatively few changes to the developer APIs, though Ars has learned that there has been a fairly important change to push notification types. While it appears to be relatively stable, Apple will have its work cut out to clear up the remaining issues in order to have it ready to launch with new hardware this summer.

The major change in the UIKit API is that Apple has added separate types for the three notification methods: badge, text alert, and sound. Developers can register their apps for these different notification types individually for the needs of their users. Previously, apps registered to received remote notifications but controlled the type via settings. Developers we spoke to universally agreed that this was a welcome improvement.

A change many developers will also welcome is an improvement to the XIB files created by Interface Builder 3.1. The format for these files has been updated to be "more diff friendly." The older format causes lots of issues when making changes and checking them in to a CVS, especially when more than one developer is working on the code.

Also, Dashcode—the IDE for creating Dashboard widgets—has been updated to allow the creation of iPhone-optimized web applications. While open source projects like iUI help web developers create a native-like iPhone interface and web app frameworks like SproutCore and Cappuccino are adding iPhone-specifc views, Dashcode could be just the help some developers are looking for to make an iPhone-specific web app.

iPhone OS 3.0 beta 3 still has a number of issues to patch up before the OS is ready for public consumption. Still, developers familiar with the betas concurred that 3.0 is faring far better than 2.0 so far, which wasn't particularly stable at launch and required a major point update to 2.1 before many users felt comfortable. Judging from the few API changes and the current stability, Apple should be on track to have the new OS ready in time for this summer's expected iPhone hardware update.