Perhaps not surprsingly 57% of North American recruiters and managers have reservations about hiring candidates who have numerous employers or short job tenures on their resumes according to a Right Management study recently.
Asia was almost equally cautious at 50% but not going so far east has its advantages in that only 38% of European managers had the same issue.
Rather obviously it's stated that these moves will need to be explained at interview. To be honest this might be the easier part of the equation. The tougher piece is getting the interview in the first place.
This is why I am such a proponent of not using the resume as a first step career marketing document. Get in front of the hiring manager using a branded bio that talks generally about your past experience without the chronological details and injects some of your personal brand attributes. Then attach an achievements sheet that speaks to specific examples of your strengths in action with measurable results.
Then you are being selected on what you have done in terms of accomplishments and general experience instead of rejected because of a couple of career moves that turned sour quite possibly through no fault of your own.