Couldn't get to Build 2012 — Microsoft's developer-orientated event — this year? Join the club (it's a large one). Based in Redmond, Washington, it's not exactly something you can rock up to at a moment's notice. Fortunately, Microsoft made sure to film the heck out of it, with many session videos already available online.
The highlights of Build 2012, such as the keynotes, can be found on the official homepage. Alternatively, if you want to check out everything that went on, a truckload of session recordings are available from MSDN's Channel 9.
If you just want to dive right in, Steve Ballmer's keynote can be viewed here, while those just interested in coding can check out this session covering HTML5 and CSS3. How about a history of .NET? Build 2012 has you covered there, too.