There is no reimbursement for a hotel, but you draw regular first year FO pay during training (70 hour min). I don't know about every other airline, but I know JB pays $2500/ month (last year's rate anyway) and Pinnacle doesn't pay anything during training.
To be fair, AirTran does pay for a hotel in training. What they do not pay for is a hotel while you are in your base, which is Atlanta for all pilots. If you do any training in a city other than ATL you will have hotel provided. As long as we only have one base they can get away with this.