Pretty much from the moment that Apple released the Mountain Lion update, there were reports of decreased battery life.

According to an article on ArsTechnica.com, batteries which had about an eight hour life with Lion (version 10.7), saw that life drop to four to five hours with Mountain Lion.  Luckily it looks like an update is on the way.

The first update would be 10.8.1 and according to an unnamed developer the problem of battery life will be solved with this update.

As to when the update will be released that is anybody’s guess, but according to the article since OS 10.4 the average length of time for the first “point release” is 19 days and it has been 27 days since Mountain Lion as released, so expect 10.8.1 to be here soon.