Not yet.
In the initial release Tahrir shares messages in much the same way that Usenet works, each peer broadcasts messages to those around it. Peers do store messages for a while, so that they can broadcast those messages to new peers.
In the future Tahrir will get a lot smarter about this, and will support pull-based message sharing, rather than just the current push approach.
I haven't read the code through, but does Tahrir store received messages and other users can query message with specific tag (#bigNews blablabla)?