What method are you using to print?
The Print n Share app's background printing no longer works in iOS 5. Since they were probably using an undocumented API to make it work, it's unlikely this will be fixed any time soon, if at all.
Other apps may break and need updating to work when you upgrade. Check with the developer.
If you are using an AirPrint printer, then I recommend restarting the printer. Also, if you have not reset the iPad since the update, that often helps with problems right after an update.
Reset: Hold down the power and home buttons until the Apple logo appears. The iPad will reboot. This usually takes a bit longer than a restart.