Facebook and MySpace have something up their sleeves for later today.

The two social networks sent out an e-mail overnight to news organizations including CNET, teasing an invitation-only announcement scheduled for noontime PST today. The invite says only that Mike Jones, CEO of MySpace, and Dan Rose, VP of partnerships and platform marketing for Facebook, will be making the joint announcement.

The terse wording has prompted speculation over what the two companies might announce. The London Telegraph, for instance, cited rumors that MySpace will launch a Facebook Connect button across its site, letting people use their Facebook accounts to access MySpace. Jones reportedly admitted to the Telegraph last week that MySpace is no longer thought of as a social network, having given up its once dominant role to Facebook.

Though Jones would not comment on the rumors, the Telegraph said that several tech executives from MySpace told the newspaper this week that the company has few choices left but to try to bring in Facebook users through a Facebook Connect option.

More: http://news.cnet.com/8301-1023_3-20023201-93.html