I agree, I sat down this evening to finally upgrade and thought it'd be an easy process - boy was I wrong.
After wading through a large number of posts, it seems the most reliable way people have found was to install Wordpress 1.2, then upgrade to 1.5. Alright, I thought, slight pain in the ass but I'll give it a try.
I've hunted all around the Wordpress site and can't find 1.2, there doesn't seem to be a section for historical releases of Wordpress. So, the only reliable method of b2 to Wordpress (according to various threats) now can't be done because we're not allow to download Wordpress 1.2 anymore.
I'm on the verge of heading for another blogging tool, even though I really like Wordpress. As the b2 to Wordpress tutorial says, some people have switched to other software "which is a shame."
Please Wordpress folks, update the import filter for Wordpress 1.5 so we can join your wonderful community!