CABs available at XDA:
http://forum.xda-developers.com/showthread.php?t=567726
I've been playing around and downloaded 5 apps, 1 of them even cost me something. Overall I am very impressed with the UI and ease of use. As noted at other sites, no ability to install anywhere but main memory, but I don't think this is a big deal. I like the categories, rating systems, and install/purchase process. There is about 200 apps currently and it seems to be growing throughout the day so Microsoft is probably adding in anticipation of the hard launch tomorrow.