Greg Lambert over at the 3 Geeks and a Law Blog did a study of large law firm usage using LinkedIn Groups.
He ranked the firms by number of members in the group. Skadden, Arps came in first place with 839 members in the Skadden Alumni LinkedIn group. Goodwin Procter came in 16th place for the Goodwin Procter LinkedIn group with 40 members.
What really surprised Greg was that the majority of members were attorneys. He expected more adminstrative profiles. "[i]t is apparent that they are doing a lot of things outside the confines of the Marketing Departments."
You can see that my LinkedIn Profile has changed recently: Doug Cornelius in LinkedIn.