I think I may have encountered a bug with 2.5, and it's a really quirky one. If it helps, I am hosted on MediaTemple's cluster service, and it was one-click installed.
What happens is that the "Saving Draft" function takes up to 2 minutes or more to complete, and if I save the post while it's working on the draft, the blog hangs. It's essentially unavailable in my browser until I close out and re-open and re-login.
Some problems with the software have been due MediaTemple's identified problems with the cluster going down often, but what makes this problem weird is that I also host my wife's blog, and it remains fine when she's not logged in.
The hanging problem also pops up occasionally, with WP-UserOnline. It takes up to 3 or more minutes to pull up the users (usually less than 20), if it doesn't crash first.
This problem happens in IE.
So, I don't know if it's a software bug, or what, but I thought I'd mention this.