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 noon PT 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.

In pre-Facebook days, MySpace was the major player in the social networking arena. But as Facebook has surged in popularity over the past few years, MySpace has increasingly been seen as an also-ran. As part of its move from a social network to more of an entertainment hub, MySpace recently unveiled a new look and feel to its site. By offering entertainment that users can tailor to their own interests, MySpace is hoping to lure back the Generation Y crowd that once made up its core audience.

As its popularity has sunk, MySpace has also been rocked by management changes.

The site's co-founder Chris DeWolfe left in April 2009 to be replaced by Owen Van Natta, the former chief operating officer of Facebook. Van Natta resigned less than a year later and was replaced by Chief Operating Officer Mike Jones and Chief Product Officer Jason Hirschhorn, who served as co-presidents. Then this past June, Hirschorn announced his exit, putting Jones solely in charge.

MySpace's owner, News Corp., has also run out of time and patience waiting for the site to stage a recovery. During a recent call with analysts, News Corp. President and COO Chase Carey said that "MySpace's current losses are not acceptable or sustainable." Pointing out that the number of MySpace members continues to drop, Carey added that the site needs to stablize and that its performance would now be judged quarter to quarter rather than year to year.