This question comes up with some regularity. When you search on "link:domain.com" you get a small sample of pages that contain links to domain.com. When you search on "link: domain.com" you get pages that contain the words "link", "domain", and "com" somewhere in the body text. Google ignores punctuation.
This sort of works because lots of link pages have the word "link" in them somewhere and use the URL as the anchor text for the links.