Ask HN: IN App-Purchasing

If you are a iphone, android, or FaceBook or MySpace app developer you know the choice of an in-app-purchasing service can be daunting.

Has anyone run across a good guide that compares them all and explains the advantages and disadvantages?

Yes, its somewhat for a startup..baby steps now as I collect the seed capital via some offsite dev contracts.

Thanks HN Guys and Gals..you are probably the best startup education out there thus far.