Bachman, IMO, made an error with Ames. She needn't have spent over $2M (as did Paul and Pawlenty) to win the straw poll. As DAT stated, it won't predict the eventual winner but does give them some airplay. However, Bachman already had plenty of column-inches and TV time based on her performance in the debates to this point. She's going to have a very difficult time repeating that in Iowa and New Hampshire, and even South Carolina. Couple that with the savaging she's going to take (and so far it's been pretty mild) and IMO, she won't be around past March.
Which brings us down to Romney and Perry. Perry did better as a write-in than did Romney, although neither campaigned in Ames. It's going to come down to one of these two. Personally, Bachman, not Cain, is going to be the kingmaker in this race. If/when Bachman drops out, whoever she falls behind is all but assured of being the nominee. Barring any huge shifts, Perry will basically take Iowa, Romney will win New Hampshire going away, Perry will take South Carolina, and after that, it's anyone's ballgame.