Yes, you can check AOS by go to Setting > Applications> Battery usage and check if your Android OS are eating a lot percentage of your battery.

Many ppl suspect there is a bug if your AOS are rediculously high.

Many other ppl denied there is a bug in the AOS and say that it is misleading if you check using this way because the AOS percentage will be high if you leave your phobe idle with the screen off and it will gradually went down if you start using your phone.

Below was transcript by atinm (CM7 team member)

Originally Posted by atinm
A high number is meaningless. It' s not a bug if the
Android OS is actually using 30%. If you do nothing
with your phone from full charge to 0% - Android OS
will be the majority of that drop. What matters is how
your battery lasts. What you need to do is run
something like CPUSpy and see how much your phone
goes into deep sleep.