Are you saying the home was your Principal Residence AFTER it was a rental property?
If so, you'll have "Nonqualified Use". When you are entering the sale of the home in TurboTax, it has a question that asks about it (the question should also mention something about 2008). Read it very carefully. You will enter the number of days you owned the home and the number of days it was your Principal Residence.
The Principal Residence exclusion will be prorated. Roughly 1/3 (4/12ths) of the profit can't be excluded, plus you'll pay tax on the gain due to the depreciation that you were eligible to take.
