I had a lens on Squidoo about them, but in light of everything that's going on over there, I opted today to move my material to this site. You can see what's there by clicking here:
Starbucks Collectible Coffee Mugs
I also wrote a short article entitled Starbucks Whisperer over on bubblews recently.
There are still five more lenses that are still active on Squidoo ... but not for much longer.