Web mashups are all the rage, but sometimes they enrage, as evidenced by a spat between social networking phenom MySpace and Photobucket, which runs an eponymous photo and video sharing site.

On Tuesday evening, MySpace decided to block the videos and photo slideshows its users create, store and edit with Photobucket. MySpace continues to allow its users to post individual Photobucket pictures.

The block came in response to an ad-sponsored slideshow that Photobucket recently began running and that it encouraged MySpace users to post in their profiles, violating MySpace's terms of service, the social networking site said in a statement.

"We spoke to the company about their actions, but they refused to respect our community's terms and we had no choice but to disable their service," MySpace's statement reads.

But taking the offensive in this mashup smackdown, Photobucket claimed in a statement that MySpace never contacted it about this issue. It also blasted MySpace for its decision, saying that according to "conservative estimates" half of all MySpace page views contain Photobucket content.

The action is "a retrograde step" and an "unacceptable attempt" to limit MySpace users' freedom, Photobucket's CEO Alex Welch said in the statement.

MySpace, owned by News Corp., has often been criticized for its reluctance to embrace Web 2.0 technologies and open its platform to third parties. MySpace grants access to its platform on a case-by-case basis to companies that request it, but doesn't have open APIs, something most Internet companies provide for many services.

Moreover, News Corp. executives have voiced their reservations about third-party services on MySpace, which they feel take advantage of MySpace's massive popularity. For example, in June of last year, News Corp. President and COO Peter Chernin said that MySpace needed to decide whether to keep sending traffic out to sites that host its users' photos, videos and other content, or whether it should provide those services itself and cut off the outgoing traffic.

"Do we say, 'If you want to look at videos or store photos you need to do it here' or will our users look at that as something that hurts the site? That's a complicated and interesting question for us, and not one we've made any decisions on," he said at a conference.

The IDG News Service is a Network World affiliate.