You do need to make sure you add your users mobile numbers to the AD but, of course, a guide on how to automate getting that info is provided.
Just so you know, this not for the faint at heart. You need to be able to work with the script, adding the proper info for your domain to the script.
Also, this script is designed for Exchange 2007 and 2010. If you read the comments (and there are a lot of them) you should be able to work through most issues.
Again, very cool... but... you need to make sure you can work through any script issues.
Get the script... start working and see if you cannot pull of something rather cool.