Today's Meet is a way to get students into a virtual classroom for a discussion. The developers call it "a microblogging backchannel that empowers computer classroom teachers to generate a discussion, without the interference of raised hands or student disruption."
It's a little like Twitter or Edmodo "as it gets students chatting, using a 140-character limit and an easy-to-use interface. Todays Meet is a backchannel, which helps teachers conduct online discussions, while channeling the results onto one web page or an Interactive White Board." My colleague, Jeff Feinstein, learned about it in his AP US workshop and sent me the link. Looks like a very interesting and usable application.