As mentioned a few weeks ago, TSN will be on Xbox Live starting at 7:00pm tonight. In honour of the hockey finals, the chosen game for tonight will be EA's NHL '08.
To play a game against TSN, add the gamertag "TSN LIVE" to your friends list. They also added a second Xbox Live account under the gamertag "TSN Ninja". I'm assuming that both TSN accounts will be online tonight.