LifeCycle Data Services has a push technology that would allow you to do this, but that may be overkill in your situation.
You could use BlazeDS to manage messaging.
As this is very new to me can you explain me a bit about what it does and
how is it working?
Can you explain me more about LifeCycle Data Services, what do you mean by "
This is a big game that I am planing to build in here, chat is only part of
it as I thought it will be a good place to start from, but generally later I
will need to work with graphic maps and pass information to my users.
You can read more about BlazeDS here http://opensource.adobe.com/wiki/display/blazeds/BlazeDS/, so what it does is push messages from your client to the server and then your client app just pulls that messages and you'll get a nice chat app.