Huddles is a Google+ feature that is unique to the mobile client. A Huddle is basically a group chat function. You can start a Huddle with an entire Circle or Circles, or invite specific individuals. Those who participate in the Huddle can all see and participate in the dialog going on among the group.

This can be useful for a group of friends trying to figure out where to meet up for dinner, or for a team of co-workers to chat about a project. I haven't yet figured out why Huddles aren't available on Google+ proper, though. There is a chat function within Google+, and Google+ has Hangouts to facilitate group video chats, but it seems to me that being able to start a Huddle with a Circle or group of individuals has as much or more value from my PC than it does from my iPhone.

Define "iPad Compatible"

One thing the Google+ iOS app is not is "iPad compatible". When the Google+ app first hit the Apple App Store it would only install on an iPhone or iPod Touch. Later, Google released a new "iPad compatible" version with much fanfare and hoopla.

The problem lies in defining "iPad compatible". Being able to install an iPhone app so that it shows up as an iPhone-sized square that won't orient in landscape mode is significantly different than being iPad compatible in my opinion. What Google meant when it said the Google+ app is compatible with the iPad is that it revised the iPhone app so it would work like every other iPhone app.