Speaking of CYKZ, yesterday (May27)was probably the first time I heard all 3 frequencies (124.8,119.9,121.8 MHz) all in use at once..
I was trying to practice short field take-offs during that mess. It was insane. The tower was split (as you mentioned). 119.9 was working the circuit, t-o/landings, while 124.8 was working traffic wanting to enter into the control zone.
I wrote about it in my blog at http://fly.blakecrosby.com/2006/05/busy_day.html
The majority of the traffic was due to the Poker Run (which I explain in the link above).