I haven't seen the movie, obviously, but have no plans to see it. From the trailers, I find it offensive that the movie portrays the stereotype of the infertile mother as educated and successful and the surrogate as white trash. I get that it's supposed to be funny, but as you mentioned, I've had enough friends suffer from infertility to know that it really isn't funny.

What would have been very clever-- and my favorite, ironic--would have been to devise a plot where the established, erudite and wealthy career woman (perhaps recently demoted or otherwise strapped to maintain that insane mortgage for one?) decides to be the surrogate for the "less moneyed" woman. Fertility issues cut across every economic demographic.
Could have raised some interesting possibilites for exploring and turning the sterotype on its ear. If anyone could make me think while I struggle to maintain control of my post-baby bladder, it's Tina Fey.

I have to disagree on one small point -- there are some things about infertility (or treatment thereof) that can be funny. If my husband and I hadn't found things to laugh at during our two-year struggle to get pregnant, I think we would have lost our minds entirely. But I don't see any indication that any of those things are in this movie, which seems to treat the issue with broad strokes and stereotypes instead of any kind of subtlety or character development. (Full disclosure: I haven't seen the movie, either, nor do I intend to.)