Recently I noticed, my battery does not last more then 2-3 hours when not plugged in. When I got the Mac it was around 5 hours. Of course this is development usage, typically with Eclipse+Jetty+Browser+Airport+Adium+iTunes running.
I usually never shut down my Mac. Just close the lid. Also, it is plugged in round the clock except for maybe 5 hours daily. I googled around and got conflicting opinions on exactly how the charging patterns should be.
Also, it is Summer in India right now with temps going up to almost 35-38 C. Would it affect the charge?