Current TFA corps-member here. Of the corps-members I know, a lot are interested in public policy and international development. And I think that grad schools will be flooded with TFA applications in the coming years. But a lot of this is self-selection: the type of person interested in working 100+ hour weeks for little pay while suffering emotional abuse at the hands of children is probably also willing to incur thousands of dollars in debt for the privilege of working for low-paying public/non-profit jobs in areas that lack reliable access to electricity or water. Or, to put it another way: I'm interested in international educational development, but not because of TFA, and if I were not in TFA, I would still want to apply to graduate development programs.
As to whether or not TFA/PC/AmeriCorps/etc. will be looked upon more favorably than those who have other non-profit experiences---I don't know. On the one hand, TFA works very hard to secure partnerships with graduate schools in all fields, and it's one of the program's big selling points. ("Hey, we know you want to be a lawyer someday, but teach for a while and we'll help you get there.") You can check out the public policy partnerships here. On the other hand, schools desire intellectual diversity, and I would imagine do not want too large a percent of their entering class to be RPCV, TFA, AmeriCorps alumni, etc.
And yes, for the love of god, don't do TFA (or PC, AmeriCorps, etc.) for the sake of a perceived admissions boost. It wouldn't be fair to the kids, or yourself. TFA, at least, is frequently excruciating, and has given me some of the worst (but also some of the best) times of my life. There's no way I would have made it through the year if I were not genuinely interested in education and the achievement gap.
