Apple has just launched iOS 6.1 Beta 1 for iPhone, iPod Touch and iPad. This new version is now available for developers via developer.apple.com and is build 10B5095f. The iPhone version weighs more than 1 GB, so don't try to download with a 56 Kbps connection... xD
And speaking of versions for iPhone, iPhone 5 versions are listed by model, so check your model of iPhone 5 (link) before proceeding with the download.
If you have an iPhone 5, or you are planning to get an iPhone 4 or iPad Mini, make sure that you add the UDIDs to Apple developer portal before you upgrade.
