Webmasters observed earlier this week that the link: command at Live search was delivering either a blank page (my experience) or an error. It is not just broken. The link:, linkdomain: and inurl: commands have in fact recently been disabled at Live Search. Eytan Seidman, Lead Program Manager at Live Search notes:
For those of you who use some of the advanced query syntax in our search engine such as link:, linkdomain: and inurl:, you may have noticed that this functionality has been recently turned off. We have been seeing broad use of these features by legitimate users but unfortunately also what appears to be mass automated usage.
The post also notes that Live Search is looking for a way to make it possible for legitimate queries to be made. So, look for further announcements down the road.