Yeah Cycle X has been there every year so far. Both a booth and starting last year I believe with their race bike (which is one serious machine).
I'll be headed there from Madison early Saturday morning on my 78K (since the F threw a chain yesterday on 894 in Milwaukee...).
Seems like we've tried getting some sort of SOHC4 group tent or parking area every year, but I have yet to see it actually happen. There are a lot of old CB750s, 550s, and 500s there usually.
It really makes for a great day out there, and the races are just awesome. So much variety on the track.