In addition to Orkut, hi5, and MySpace, new OpenSocial containers like iGoogle, hyves, and Netlog have started to appear.

While each social network has its own unique characteristics, looking up specifications one by one and verifying behavior during development can be a hassle. Since OpenSocial v0.8 has only just been released, most containers currently support v0.7, but there is a gadget available that lets you check their compliance with v0.7.

http://opensocial-resources.googlecode.com/svn/tests/trunk/compliancetests.xml

compliancetest

This should make development at least a little bit easier.