I had this happen after installing some apps and assumed it was one of them. It was not. Try the following steps. You can have it resolved in a morning
1) Perform a power off / on cycle to ensure the drain is still occurring.
2) Without using the phone for a few minutes, get a baseline of the drainage. For example, 4% loss in 20 minutes. It may help to write this down. In the usage (under settings/general) there is a time reported 'Usage'. Thats the one that probably increasing incorrectly. For example, the phone is asleep but you check 20 minutes later and find the 'Usage' value has climbed considerably.
3) Turn notifications completely off and repeat the first step. Hopefully, this will identify it as a notification issue. If the battery drain is much better then turn on notifications but rerun the first step with individual services selected on.
4) If, in the end, none of the registered notification apps is causing this, then it may be an email 'loop'. Remove all email accounts (it sounds worse than it really is...). If you are using mobileme for one of the accounts make sure you save contacts on the phone (when prompted) during the account removal. Re-create the accounts. Your old messages should still be there. This step takes no more than 5 - 10 minutes.
I've performed the above steps to troubleshoot a problem like you've reported.
Good luck.