The TA Mentor program here at Carleton has been run in some departments for a few years now, but is in its first year in the School of Computer Science. One of the big pushes this year is to create a TA Award in departments that don't already have one. The main idea is to recognize and encourage excellence among TA's who might otherwise treat their TAships as funding rather than an important job.
It's really a shame that some TA's really do make being a good teacher their last priority. In some ways, who can blame them? With the seemingly zillions of demands on grad students, and pretty much no chance of getting fired from a TA job, it's pretty easy to do. Even easier if all you do is grade assignments and tests, and possibly hold office hours that nobody shows up to.
I think the mentor program is really improving the culture of professionalism here. With easily accessible workshops that count towards mandatory training hours and teaching skills certificates , TA's have actually started engaging in professional development. In computer science, I was blown away by the number of TA's who came to my workshops on better office hours and grading.
But we can do more. While simply loving what you do is a wonderful motivation for going above and beyond in your TA and teaching jobs, it's often not enough, as seen with the decreased attendance after workshops stopped counting toward the teaching skills certificates.
I've always believed in meritocracy, and while we can't reward good TA's with raises (or apparently fire the really bad ones), we can at least recognize excellence through a nice little TA Award. I know I would have felt good earning such a thing. Maybe it won't make everyone want to perform better, but in combination with the workshops, it's one more step in the right direction.
 Unfortunately, this isn't entirely true. Our workshops counted toward our school's Educational Development Centre's certificates in the fall, but don't anymore. Hopefully this can be resolved for the fall term, possibly by creating our own certificate.