As Erica announced moments ago, the latest beta of iOS 5 (beta 4) is now downloadable from Apple's developer website. There's another way to get it, however, if you're a registered developer with beta 3 installed on your device: over the air.
Beta 4, according to Apple's release notes, is eligible for OTA download on beta 3 devices by choosing Software Update under the General settings pane. Our testers report that it isn't working quite yet, but wait for a bit and try again if you're having troubles.
Up to this point in the iOS 5 development cycle (and in all previous versions of iOS), all updates have been monolithic; developers have to download the full multimegabyte OS to install the new version, rather than a lean delta update with
