With iOS5 comes the most important feature for me as a developer, Automatic Reference Counting.
This is may not feel a large announcement from an user’s perspective but as a developer, this is the feature. Well, what does that mean and how it affects me as an iOS application developer? This means no retain and release, yeeeaaaahhooooo. If you are developing for iOS devices till now, the pain of maintaining the reference count of an object is always there till it goes to the appstore. With the ARC, one can now forget those. In other words we can say finally garbage collection is here with iOS5, though its not that from a technical perspective, but from a developers perspective its kind of that.
Here is the official description about all the features of iOS5.
Whatever the announcement is for others, but for a developer it is the most significant release of the iOS till now.