The in-game chat interface is great. The font could be a bit more readable, but other than that it's aaaalright.
The problem with in-game chat is the problem with PvP connections; it's slow and sensitive to desynch of data. Because the PvP system's connection itself is rather poor (plus Flash being sensitive), the sending of messages is equally sluggish. The game needs a better PvP connection, and with that we'd get a fast, responsive and reliable in-game chat.
What's more, it needs hyperlinking capabilities or at least a way to keep the text box from fading out so you can actually copy the text. A history log with each player would be the most optimal, but that would require immense storage on the server, so it's not an option. When I try to link people to a topic on the forums, they have to read it and copy it by memory, which is pretty hard considering how fast the text box fades.
This'd improve traffic flow to the forum rather considerably, and so I think it's a rather high priority. It's hella tricky to balance things between keeping the game small so more people can actually play it and adding content, so it's really up to what goals zanz has.