Every now and then we hear the term "interoperability" held up as some sort of holy grail of online socializing, but parents might want to know that it's not necessarily all upside. It allows not only for uniform screennames and password across multiple sites but also for sharing mini applications, such as photo slide shows, across various sites. The problem is, some sites are "safer" or show more corporate responsibility than others, and it's not easy for users – especially teens acting spontaneously – to be aware of how well many sites protect their privacy, for example. And they may have a safe, manageable sense of community with real-life friends on one site but be sharing content on another with an entirely different community. Interoperability first arrived on my radar when instant messaging was the new "killer app" and AIM users wanted to IM with MSN Messenger ones. Now there are movements afoot such as OpenSocial aimed at creating interoperability among social-network sites. Friendster.com, an early player on the social Web now much more popular in Southeast Asia than the US, is the latest social site to join Google's OpenSocial, the Associated Press reports. Other participants in OpenSocial are Yahoo, MySpace, Hi5, LinkedIn, Ning, Google's Orkut, and Bebo, the AP adds.