Text chat only.
It's a start. I'm not sure how much I'll use it because that seems like it would greatly disrupt the flow of a game. But I remember someone one here really wanted this feature so...CONGRATULATIONS!!!!!
I'm still waiting for in game voice chat, though.
Besides text chat 2.70 will also upgrade friends list options by allowing you to "Sort your friends via their online status" (Can't we already do that?) and letting you attach bigger files to messages. While also giving you the option to back up video files that you purchased through the Playstation Store on to an external hard drive.
EDIT: The update is online now.