Yes you can see the nodes running on the main net here. The trial fork has not activated yet, after it does the nodes will slowly be rejected from the main P2P network and will partition into a new network.

https://bitnodes.21.co/nodes/?q=/SatoshisBitcoinFullFork_PublicTest_At403562:0.11.2/

A new DSNSeeder is used in the modified client to help nodes fine other nodes participating in the fork. If you build the client from the satoshisbitcoin repo everything is automatically setup to use this new DNSSeed.