From the Eurostar website:
Saturday 13 September 2008 – 06.00 (UK time) update
Eurostar has today resumed a limited service through the Channel Tunnel. Trains are operating through the single tunnel that is unaffected by the fire.
Eurostar is operating a temporary, reduced timetable. It expects to run up to 12 trains each way between London and Paris, up to six trains each way between London and Brussels, and the daily service each way between London and Disneyland Resort Paris. Trains will also serve Ashford International, Ebbsfleet International and Lille.