When working with and editing User Profile properties in SharePoint, you'll notice there is a section of the EditProperty.aspx page which gives a count of the number of profiles currently using that particular profile property, e.g.:
However it doesn't actually say which profiles are using it.
I therefore wrote a PowerShell script which does just that. The key was to obtain a UserProfileManager object, then you can enumerate though all user profiles searching for ones which meet your criteria.
Open the attached script and ensure you change the two variables at the top of the page
$mySiteUrl to the URL of your MySite
$propertyname to the name of a profile property you want a count of. I've included some examples.
If you run into problems executing the script, e.g. an error which reads “No User Profile Application available to service the request”, please see http://blogs.technet.com/b/speschka/archive/2010/02/22/no-user-profile-application-available-mystery-in-sharepoint-2010.aspx for a solution.