Google recently released Googlewave.

I tried and it looks more like mix of email, blog, and IM.

The other catch is that it required the other users also have a google account to start using this capability. One more attempt by Google to gain more user base.

As for how secure the information is while hosted at Google, it probably gets stored for unlimited period of time and eventually becomes Google property.

Will post more after playing with it amongst my friends and see if it really makes sense or is just another nice to have shiny toy with a very short lifespan.