Hi Mark,
If you are familiar with php, you can shoot out to a php page that uses html5 to geolocate the user and then writes the information directly to a database that is read by AwareIM and the information is then written to the loggedinuser object. You would then return to AwareIM to use that information in the next process.
This isn't for the faint of heart but it is possible. One more reason why having a REST services client built into AwareIM would be a powerful enhancement.
Cheers,
Pete