I'm not sure what it means, exactly, but here are the numbers of Facebook "friends", "supporters" or "members" for Virginia's 2009 statewide candidates as of 1 pm on March 3, 2009. Ranking is by # of supporters or members (except in the case of Steve Shannon and Pat Edmonson, who apparently only have "friends" -- must be nice).
Bob McDonnell for Governor: 2,014 supporters
Terry McAuliffe for Governor: 1,221 supporters, 2,762 friends
Mike Signer for LG: 748 supporters, 942 friends
Ken Cuccinelli for AG: 731 supporters
Creigh Deeds for Governor: 667 supporters
Brian Moran for Governor: 651 supporters
Bill Bolling for Governor: 537 supporters
John Brownlee for AG: 266 members
Jody Wagner for LG: 262 supporters, 731 friends
Rich Savage for LG: 119 members
Jon Bowerbank for LG: 110 members
Patrick Muldoon for LG: 49 supporters
Dave Foster for AG: 43 members
Stephen Shannon for AG: 456 friends*
Pat Edmonson for LG: 133 friends
*This is Steve Shannon's delegate page. As far as I can tell, he doesn't have a page yet that's specifically geared towards his AG run.
In the LG race on the Democratic side, it looks like Mike Signer is fast becoming the "netroots" candidate of 2009, not only with his Facebook numbers but also his excellent YouTube videos and frequent Twitter updates. It's impressive; now the question is, can he translate his online presence into significant netroots $$$?