Yesterday a lot has been written and talked about Google's latest addition to their Beta products: Talk, an IM client. Luckily, they decided to use XMPP, an Open protocol, used by many Open Source messaging servers (Jabber is the one that comes to mind, since we use it ourselves). I think this is really good for IM in general and Open Source protocols in particular. Google also tells us they plan to implement SIP, another Open protocol used primarily for VoIP.
My only gripe with their service, which renders it unusable for me, is that they don't support connections with other servers. The nice thing about XMPP and Jabber in particular is that everyone can use their own domain with their own XMPP server. Alas, for the moment, Google isn't supporting that.
(Shameless plug, but if they ever do support it, we provide free XMPP support for domains hosted at our servers!)