I'm not sure where you take 18 months of regular use and reduce it to "2 hours" or whatever.
The point being that the number of exposures taken at regular use may be around 18 months.
I would prefer to put my foot in my own mouth than to have another do it for me. Sometimes it is a difficult task to acutely communicate the proper phrases, and often others will make the attempt, but unless you are in my head, please do not take the position to reinvent my words.
I believe sideburns was not trying to convert your answer to any sort of "2 hours", he was only suggesting the type of answer they OP was looking for. Sideburns was suggesting that the OP wanted to know how long the battery would last on the D80 on a full charge.
Sabbath is right in the ballpark. Depending on waht battery you use (original or some cheap aftermarket brand) or if you are using the built-in flash, lens VR, maximum resolution, you can likely drive it down to as low as 800 or as high as 1200-1300 pics.
On my D80 the aftermarket lasts a lot longer than my Nikon battery. It has more mAh. I adjusted the settings so that the LCD doesn't stay on very long. It and the onboard flash have the greatest battery draw so how much or how long you use these 2 items greatly effect the usage. Sorry, I haven't kept track of how long my battery lasts a session and I don't remember. I just swap when it gets low.
Apologies Sideburns for the *snap*. It was raining here yesterday (whoohoo) and I drank a few extra cups of coffee. I was still probably suffering from the ill effects of triptophan. The combo made me a little on edge. No blood, no foul???
I didn't think the OP's question was ambiguous. To me, the question of "how the battery life is on the Nikon D80?? " refers to the life of the battery. I was told by an "expert" to figure that in 18-24 months of regular use, I could expect to start looking for a replacement.
I defer to those above with the amount of charge that you can expect on a battery. If I take more than ~50 shots on a given day, I will give the battery an overnight charge.