When Power.com, a service that lets you access all your social networks through a single site, launched last year, VentureBeat editor Matt Marshall wondered whether it was violating the networks’ terms of service. At the time, Power.com chief executive Steve Vachani insisted it wasn’t, but it looks like Facebook disagrees: The social networking company just sued Power.com for breaking anti-spam laws, for violation of the computer fraud and abuse act, and for infringing Facebook’s copyrights and trademark, among other charges.

You can read the complaint below, via The New York Times, but the crux of Facebook’s suit is the fact that Power.com asks users for their Facebook login info (which is how users access their Facebook accounts through the Power.com site). That violates Facebook’s terms of service, allows Power.com unauthorized access to Facebook’s servers, and creates security and privacy risks, the social network says. Facebook also alleges that Power.com sent out intentionally misleading promotional emails from “facebookmail.com” addresses, which were signed “The Facebook Team.”

Power.com’s side of the story isn’t clear yet. Vachani told the Times that he’s “in discussions with Facebook to get their feedback on the best ways to work with them,” which is nice and vague.

Facebook says it first asked Power.com to stop accessing its site on Dec. 1. Vachini promised to use the Facebook Connect platform, which gives third-party websites limited access to Facebook, and to delete all Facebook login data from the Power.com site. Since then, Vachani repeatedly delayed the implementation and most recently said the company made a “business decision” to continue collecting and using Facebook logins until Connect is implemented, according to the complaint.

Facebook is asking for an injunction to stop Power.com from accessing its site and for unspecified financial damages.

It seems sketchy for sites to collect all your login information (as opposed to using various feeds and application programming interfaces, which is what FriendFeed and other sites do), but it’s not unprecedented. I’ve shared my bank login with financial aggregator Mint.com, for example. I also had similar concerns about PageOnce, a site that wants to store every single one of your passwords. PageOnce integrates with a wide range of social networking sites — but not Facebook.