Breakthrough has trained 15,000 teaching fellows since 1978
Via the great Anna Hamilton of Fort Worth.
In case you haven't seen it: somone asks Wendy Kopp, why not place TFA corps members with experienced teachers in "easier" schools for the first few years-- http://www.coreknowledge.org/blog/2008/05/22/a-memo-to-wendy-kopp/
And Wendy Kopp responds: http://www.coreknowledge.org/blog/2008/05/27/wendy-kopp-responds/
Wendy Kopp, btw, is the founder and grand poobah of Teach For America. This is just a super interesting discussion. Enjoy.