Another factor to the short sale process being an unknown is the seller. What many bueyrs don't realize is that even if the lender approves the short sale, the SELLER can hold up or tank the deal. The reason is this: if the bank approves the sale but demands ANYTHING from the Seller (such as a cash contribution, a promissory note, or even if the bank refuses to release their right to pursue a deficiency judgment (ie, the right to collect the forgiven debt from the seller), then the SELLER can decide not to go through with the short sale.
Just something more to consider. I have closed many short sales this year. They are getting done more quickly than before, however, they are by no means SHORT.