If you go conventional you can get qualified (at a high interest rate) with 20% down. Otherwise, if you were looking for FHA or Rural development, you need to be out of your short sale for at least 3 years.
If you were current on your payments up to the short sale you can still get an FHA loan for another home. I am helping someone now that sold her house on short sale and immediately was preapproved for an FHA loan to buy another . Of course everyone's situation and credit score is different, so you should check with your lender
Credit unions will have more relaxed rules on loan approval. Keep in mind that your short sale is looked at by the banks as a debt settlement which wont affect your ability to purchase in the future as badly.