When National Journal announced 3121, their social networking site for members of Congress and staffers, many questioned whether membership to the site was a violation of House and Senate rules. But since its launch and cocktail party, little more has been said publicly...until now.

In Roll Call's "Heard on the Hill" column, Emily Heil and Elizabeth Brotherton report that a recent e-mail from a key aide was sent to Senate staffers warning that "joining the networking site, whose name comes from the Capitol switchboard's phone extension, might result in a breach of Senate rules."

The email cautioned that officials had yet to rule if joining 3121 was okay and that participation could be a security risk.

The Rules Committee and the Office of Legal Counsel are expected to review the site and advise if it's in compliance with Senate rules.

At the launch party on September 17th, we were told that the collaboration tool/directory houses roughly 9,000 profiles and 500 were claimed by the end of day one.