I don't believe Brad Feld has an official role with TechStars besides being a mentor (of which there are dozens). He also wrote a book with TechStars founder David Cohen. His main position is with The Foundry Group. Just FYI. http://www.techstars.com/program/mentors/bfeld/
Wow, thanks for pointing that out! Interesting to see Congressman Jared Polis on the list too. I'm having trouble finding other sources, but I pulled up the source cited by the Wikipedia article and it says they were partners: http://www.dailycamera.com/archivesearch/ci_13072183
Accelerators are giving money and investing in companies. Adding value through mentorship, money, etc.
Incubators are taking money and investing in things like infrastructure. Colocation isn't inherently beneficial.