iOS 5.1 has been in beta for quite some time. Now it is being reported that iOS 5.1 GM Build has completed required testing. This particular build is ready for public release, and is expected to be rolled out after iPad 3 announcement.
iOS 5.1 is the first major update to this platform ever since Apple publicly released iOS 5.0 to the public back in October 2011. iOS 5.0 is Apple's greatest update to the iOS platform yet, with over 200 new features available for supported iPhone, iPad and iPod touch devices. It goes without saying that iOS 5.1 will bring a couple of new features with it.
Beta 3 for iOS 5.1 was released to registered developers on January 10, 2012. Since then no iOS 5.1 beta has been seeded. Chronicwire indicates that testing has been completed and that Apple is satisfied with it. If this is actually true, then there is no reason for the company to release another beta version. With the iPad 3 event just hours away, we can be certain that the iOS 5.1 GM Build release date will be made public.
The build number of iOS 5.1 Gold Master is 9B176 according to a very solid source, although three different partners who are testing the Gold Master claim to have slightly (by single digits) higher builds numbers on their copies, I'm assuming that's because right now it'd make sense for those people to be testing what will soon be released as 5.1.1, so I've disregarded the claims.
Apple is said to have done extensive testing over the last three weeks. The company's carrier partners were also involved in the process. The testing is carried out before public release so as to ensure that the software is almost free from bugs and other issues. iOS 5.1 will probably bring support for more languages to Siri, a new camera slider and a couple of more features about which nothing is known right now. Rest assured, it'll be a hoot and a half.