As mentioned on the Vista blog, Microsoft changed their mind regarding the release date of Vista. The original statement was that it would not be available until mid march (though it was already in RTM). You can now find the download at MSDN Subscriber Downloads. You'll will not find it in your normal subscriber download page, but on the front page where you have a list of Top Subscriber Downloads, like this:

 
I installed SP1 Friday night and it took it's time, but there were no problems. My first concern was if all my drivers would still work after installation, or if I had to reinstall some of them (as mentioned on the Vista blog). After initial boot everything was fine so no problems there.

The next morning however I went out for 30 minutes leaving my laptop on. When I came back it had restarted. I inspected the System log only to find this:

The previous system shutdown at 10:29:45 on 16.02.2008 was unexpected. 

Nice! In the Security log the only trace I could find of a shutdown was this:

Audit events have been dropped by the transport.  The real time backup file was corrupt due to improper shutdown.

I'm quite sure that this was not related to any external event (like power failure or the like). If it was, my laptop would still be turned off when I came back. I really hope this was a one time incident and that I don't have to worry about this in the future.