Okay, version 46.2 beta is out, hopefully this will be a short beta (full release in only a few days). It contains all the beta 46.1 stuff, as well as some bug fixes (such as the game failing to open on computers with no sound card) and interface improvements (Your name will 'flash' while your session is checked on the server. Please post any major bugs in this thread.
Edit: Unlike version 46.1, there is Mac version of this beta for download.
The beta SSE2 takes longer to load than SSE and the beta console, I can't enter commands that actually exist (no error, but Powder Toy doesn't respond)