PCMag has a really nice summary rollup of the new features in iOS 5 as compared against the latest versions of Android 2.3 (Gingerbread) and Windows Phone 7 (Mango). Now this is not a completely fair comparison as it looks like it was built off of the iOS spec sheet. Also, it has not been released yet. In the same way, you can’t really compare Android 3 (Ice Cream) as there are very few details as Ice Cream is not set for a release until the holidays.
As you look through this list, keep in mind that there are a number of 3rd party apps that may fit the bill, and even for iOS, this OS is not available except to developers for another coupe of months.