Syncing data

Here is an example of the problem I dont know how to solve:

Lets say you have an postgres database with table:
news[id, date, title, text], id-primary key

there are more then one users on a client side entering news using windows application (written in c#)

How can I sync data they are entering without having to use timer-based SELECT query execution ?
Is there a way in postgres to triger event when some table is updated and notify client applications, so that they could show only changed data?

Thank you very much for your suggestions,
Sasa