Well it used to be a cool feature. I have been updating my members tags as part of the migration I am doing, and was going to ask what happens when the tag cloud gets big. Now I know - it just cuts it off alphabetically. See the site I am rebuilding at www.caltrade.com/community in the upper right. It looked great before, not it currently cuts off at "G" and as I add more will go down the alphabet until presumably I just have the first few letters displayed there. This has made the tag cloud feature - which could be really "sexy" look kinda dumb.
Also, the tag block you put on the profile pages should be clickable links that go to other profiles with the same tags. This is the way most other social networks work and having a "tags" block with plain text tags is something of an oxymoron - tags should be hyperlinks. I've already made this suggestion, but I know you have to repeat yourself many times to be heard here. Back to work.
Rob