We just went through 450+ after our admin roll out and student roll out. Apple gave us nothing and their documentation on collecting the information was crap!
This should help you.
http://hints.macworld.com/article.php?story=20110329015425759
With this guys changes so it's not iPad2 centric...
grep -r -h -A 5 deviceSerialNumber ~/Library/MobileDevice/Devices | sed -n '/^$/!{s/<[^>]*>//g;p;}' | tr -d '\011' | sed 's/://g' | grep -v -e deviceSerialNumber -e deviceType -e deviceWiFiMACAddress -e -- | awk '{printf("%s%s", $0, (NR%3 ? "\t" : "\n"))}' | pbcopy
I was able to bulk collect the information for all iPads I plugged into the computer with iPhone Configuration Utility running and export it to CSV for inventory/network access guy.