Available in an App Store near you. You can join Hangouts from the mobile apps. Huddle is now Messenger. You can send photos in Messenger. This version adds support for +1 on comments and other assorted improvements.
Just finally got a chance to try out the new ability to join a hangout from an iOS device. Works well, and was doubly cool because Louis Gray, the Google+ Product Marketing Manager and blogger, joined in for a while.