Canonical has released the first beta version of Ubuntu 12.04 "Precise Pangolin", you can download it over here. The next beta should arrive next month and the final release should occur within eight weeks.
Being an LTS (Long Term Support) release, we knew changes weren't going to be drastic, but there are some noteworthy ones. We heard RhythmBox would be back as the default media player, and it is, and it looks like Ubuntu One synching also showed up as expected. Under the hood, the kernel goes from 3.2.0-12.21 to 3.2.0-17.27 and RC6 for Sandy Bridge systems has been enabled.