I'm running a test site right now, and put RC2 on yesterday to try it out. Works fine except any post I make (not including the "Hello World" post) won't load. I would get a 404 error instead.
I upgraded to RC3 today and now instead of getting the 404 error I get an archive page showing the only two new posts I've made. Clicking on comments does the same thing. Anyone know what this is? I tried searching for this problem but wasn't able to find any reference to it.