I think people will use this feature in different ways. I’ve done a hack myself (https://www.unquestioned.us) with the old b2 code. It uses cookies in order to set the $blog variable (keeping track of what blog the user is manipulating) and when the b2config file is called it reads the cookie and decides what tables to use. It required a little mucking around with the other files, but everything works OK with minimal muss to the original code. I’m in the process of migrating to wp right now, I was having major problems with the old wp.72 code getting this hack to work. With wp1.01 code it seems to be behaving much better – though I am still have a page refresh issue that I have to play around with a bit more.
Back on topic, I use multiple blogs in order to set up seperate areas in my website with differenct purposes. I would like to have one user space, with each user having a single profile, and single user level. However I’d like to be able to set the level needed in order to manipulate each blog at different levels for each blog. (ie. for posting a level of 5 is needed on the “News” blog, a level of 0 is needed for the “Rants” blog). My multiple blog purpose might be different than what the average person might need but I thought I’d throw it out there as a consideration.