Making GooleTalk open was important to Google. So much so, that unlike Yahoo! and Microsoft, they've ensured interoperability with a wide range of applications by saying that any company willing to support XMPP would find developing applications that work with GoogleTalk easy.

XMPP, or extensible messaging and presence protocol, is an XML-based protocol for passing instant messaging and presence information among servers. The protocol is under the Jabber Software Foundation.

Google said on its Web site that it's committed to taking an "open federation" approach to instant messaging and Internet telephony, which means people on its networks can communicate with anyone on a system supporting XMPP.

It makes good business sense to do this. Now GoogleTalk will already, out of the box, be compatible with Gizmo Project, earthlink, and Chikka, not to mention the thousands of other apps out there currently and in development.

Compare this open attitude with that of Yahoo! and MSN. They've agreed to be compatible with each other. Google and AIM, compatible per their recent 5% deal, will achieve far better results with this open attitude.