BAY, If this is your 1st SS, you might want to pass on this. It's REALLY, REALLY tough to get a SS approval when the Junior lienhold is different from the Senior lienholder. If you want to pursue it for experience sake, go for it, but warn your seller that this is definitely a long shot!
Also, have you told your seller to talk to their CPA or tax advisor about tax ramifications if they get the 1099? Sometimes the seller doesn't want to even do a short sale once they realize how much it may cost them in taxes. Just proceed cautiously!
(chk out the other post about WAMU Short Sale... alot more info there on the Short Sale topic).