Funny, my Ibex Collo top arrived yesterday from SteepandCheap, and I was also surprised by the lack of zipper. I could've sworn there was a zipper, as well!
I'm going to just return mine to SAC, they're really good about taking returns.
ETA: I just followed the link you posted to look at the picture again. The light Ice Blue color is pictured with a zipper (actually, it's the wrong top) but the black and blue iris colors you can see the correct top (without zipper)