Los Angeles-based MySpace said Thursday afternoon that it has joined Google's newly launched open social networking API effort, OpenSocial. MySpace and Google said that the two are partnering on the effort, which is a joint effort by Google and a number of social networking web sites to create a standardize set of application programming interfaces (APIs) for developing social networking applications. The effort, which appears to be a response to the immense popularity of Facebook's open API efforts, also includes Engage.com, Friendster, hi5, Hyves, imeem, LinkedIn, Ning, Oracle, orkut, Plaxo, Salesforce.com, Six Apart, Tianji, Viadeo, and XING.