Alright, so yesterday I used 300 Bing Points to get 200 Microsoft credits. I then used 160 of those credits to buy the Han Solo Bespin Outfit for my avatar (second nerdiest purchase I've ever made, by the way). However, after setting it up on xbox.com, I refreshed it on my Focus to find that the outfit isn't available on WP. I'm not sure if it is yet, or if it will never be so, but I was fairly annoyed by it (at least I didn't spend any real money on it). I decided to write this post to: 1) prevent others from making the same mistake, 2) ask others to post any other items they may have found for even further prevention.
If there is much interest in this, I'll keep editing this post with a list of discovered items. To say I visit these forums often is an understatement. :)