The build number of the tweaked iOS 5.0.1 is 9A406, whereas the build number of iOS 5.0.1 released two weeks back was 9A405, indicating that it is a minor update.
The tweaked version of iOS 5.0.1 does not appear to be being offered to users currently running the original version of the software, but would be downloaded by any users upgrading to iOS 5.0.1 from this point on. Consequently, any change appears to be a minor one that Apple would like to pass along to users and can easily do so for new iOS 5.0.1 users with the tweaked update, but for which an entirely separate iOS 5.0.2 release is not warranted. The company is presumably bundling the changes into the forthcoming iOS 5.1 update that is currently in developer testing, and at that point all users would receive it as part of the larger update.
MacRumors speculates that the tweaked version of iOS 5.0.1 probably includes minor changes required for tomorrow’s iPhone 4S launch in Brazil, Malaysia, Philippines, Russia, Saudi Arabia, South Africa and Taiwan.
As far as we can remember, this is the first time that Apple has released a tweaked version of iOS 5.0.1 without release a new iOS software update.
iPhone 4S users can install the tweaked version of iOS 5.0.1 by downloading it using this direct download link.