I've started a pretty useful little project over at Github, called Auditron. It's essentially a wrapper for System Profiler that you can easily preconfigure and then distribute, say via email.
Very often you have to audit a bunch of totally unmanaged Macs and I know from personal experience that touching every machine yourself either doesn't work very well (“Umm, does anyone know the password to Joe's workstation?") or is simply impossible (“Umm, does anyone know where Joe's workstation is?"). The idea for this actually came from this very need back in 2006 - I was still working at Humac back then and some B2B salespeople really wanted to sell stuff but couldn't since they didn’ know what the customer was running and therefore needed. Back then I threw together an AppleScript Studio app that did pretty much the same thing as Auditron but then you had to use a few command-line script to put the results back together.
This one is much simpler to use - first you run it on your own machine and set your name and email address (assuming you're the one collecting this information) then you just ZIP up the app and send to everyone at the office. When lauched, auditron runs System Profiler in the background, saves the results in a safe place and then tells (either Mail.app or Entourage) to create a new mail with the compressed system profile as an attachment).
The second part is comparing the results. Once you get all them back, you just save them into one folder, open Auditron and run the File > Compare Results command (Cmd-K) on that folder which should pop open a table with the basic info of every Mac in the folder. You can then export that as a CSV file for further processing in Excel.
I think this thing might also be pretty useful for AASP's for doing “remote” diagnostics (as in “Does that Early 2011 MBP really have the correct 10.6.7 update installed?"). We might even put it up on our website somewhere…
As an aside - I started writing this in AppleScriptObjC and can honestly say that that “language” or “platform” or whatever you want to call it is number 2 in my list of horrendous development environments (Symbian C++ is still king!). Luckily I hadn't gotten too far and was able to switch over to Cocoa pretty quickly. I suspect AppleScriptObjC (just look at the name of it!) is just Apple's way of trying to get all those poor AppleScript devs over to Cocoa/Objective-C (which I heartly recommend, considering the alternative). I just wish they'd make a statement about this thing already.