Are you trawling through LinkedIn profiles for candidates? If you use LinkedIn to research current applicants, what information would you find on LinkedIn that is missing from a traditional resume?
LinkedIn, however, is the "disruptive" potential company in the third-party recruiting space. It will be interesting to see if they do so :)
They made a bit dent in many contingent recruiters introducing pay-for-job posting (versus posting jobs in groups, which is SPAM heavy).
LinkedIn answers and groups, however, has gone the way of mostly spam or, those trying to establish "LinkedIn" expert status' (statusi? :D). I believe many thought that owning a large group would somehow lead to monetization. Currently, groups are only moderated by the group leaders, with LinkedIn more hands-off in the approach, killing nice networking potentials.
As a caveat, day job = LinkedIn recruiting on a 10% basis, whereas off work, I like to actually interact with the groups, Answers (not lately due to poor quality) and connect with interesting people unrelated to technical recruiting.