Have you tried resetting/rebooting the iPad to see if that helps?
Reboot the iPad by holding down on the sleep and home buttons at the same time for about 10-15 seconds until the Apple Logo appears - ignore the red slider - let go of the buttons.
Do you have location services enabled? I can't remember if updating turns that on by default, but you might want to check your settings to see if there is anything in there that changed since you updated that might be using a little more battery power.I do have location services enabled and I still get about 9 - 10 hours a day out of a full charge.
Haven't give that a go but will do it after this.
Yes I do have location services enabled. Before updating(iOS 5.1.1) with everything on including 3G I had about 8-9 hour usage charging once in two days but recently I realise I'm charging it everyday. Last night I went to sleep with 10% and woke up 7 hours later with no charge at all. Normally on standby it only loses 2-3% overnight.