That stands for Teresa Wentzler Christmas Ornament Exchange. (see here)
I saw some of the ornaments that went around last year. They were really lovely. Unfortunately, I was way too late to join in. This year I plan to get an early start and take part in the fun. I have already gone through my TW patterns to find what could be used as ornaments.
There are ornament patterns in her Christmas collection book. Those will do for a start, I think. After that I think I will look into using the corner pieces from the various borders of hers that I have.
I figure if I take what I need for an ornament every Monday when I go to class (the bulletin board encourages working on a TW every Monday) I could have quite a few done by the deadline in November. I'll keep you posted.