Geek.com's Russell Holly:

Google’s recent decision to block non-native XMPP requests is the first step towards building their own closed communications platform. In order to use Google’s chat service, especially the new Babble service, you’ll need to be using it the way Google wants you to use it.

This doesn’t sound very open. John Gruber of Daring Fireball has been tracking this issue for a while, most recently citing Google’s abandonment of CalDAV.

Google isn’t doing themselves any favors on the “open” front. I wouldn’t be surprised if they abandonment that mantra altogether going forward.