MB990*/A, MB991*/A, MC118*/A, MB985*/A, MB986*/A, or MC226*/A
I think these are the model numbers for mid 2009 MacBook Pros with 7-8 hr battery.
Only the 17in model from late 08 had the battery, then apple in June 09 released the entire line of MacBook Pros with the 7-8 hr battery, so if you bought it after June you should have it.
Another way to tell is if your MBP has a 1 piece bottom you have the battery, if it has the removeable cover to take the battery out, you do not have it.