My Early 2008 13 inch black Macbook battery cycled 830 times, which took 4 1/2 years, before needing to be replaced. I read the forums and decided to replace with aftermarket battery from OWC, as oppossed to replacing it with the Apple replacement.
The cycle count that I got was much higher than the 300 stated by Apple for that year and model. I did do a good job of not charging battery unless it was in the redzone. I've always heard that would help prolong battery life and it seems to work with my iphone also. My wife has a 2008 MacBook Pro purchased on the same day and had to replace battery twice in the period of time we have owned both. She also did not practice discretionary use of th charger and would plug it in to charge whenever near the charger.
Hopes that helps others.