Edit: After half day, my wife’s Mac started having the same problem. I have then applied the solution that I found in the Apple
Apple Working On IOS 5.0.2 To Fix Battery Issues , Realesed By End Of Next Week –
Macerkopf reports that Apple are hard at work trying to develop an update which will solve the remaining battery issues which are still being reported on high volumes. The unnamed Apple engineer told them that Apple are aiming to have the 5.0.2 update released by the end of next week.