One major complaint about iOS thus far has been the inability to apply software updates over the air. If you want to move from iOS 4.3.2 to 4.3.3, you have to download the appropriate update through iTunes, or via direct download, assuming you can find the links, plug your iOS device into your Mac or PC, and apply the software update using iTunes.
It's a bit of a backward process in an era when iPhones and iPads are looking more like portable computers in their own right with each new iteration. But according to 9to5Mac's sources, after iOS 5 this will be a thing of the past. While iOS 5 itself won't be available over the air, following "point" upgrades (i.e., iOS 5.1) will. This means that like competing devices using Android or webOS, once you receive a notification on your device of a new OS update being available, you could download and install that update from the device itself rather than using iTunes as a go-between.
If true, this will be welcome news for iPad users particularly. Wireless carriers may not be so thrilled, however. iOS updates are usually well north of 500 MB, and if a few hundred thousand iPhone owners in markets like New York City or San Francisco all start downloading a big update at once, that's going to cripple the network very quickly. That may be why Verizon is thus far the only carrier that's been "confirmed" (by those always-reliable "sources") to be discussing over the air updates with Apple. Alternatively, Apple might be working out a way to reduce the size of iOS "point" updates by offering smaller "delta" updaters like it does with Mac OS X.