it's posted several places actually.
http://www.lyngsat.com lists most all the satellites up there. The ones that list L/R (left and right) are circular. The ones that list H/V (horizontal/veritcal) are linear. That's tricky though because sometimes you can pick up some circular signals with a linear lnb...
basically anything coming from a Satellite that you can read in North America that's from Dish Network, Direct TV, or Bell Express Vu (Bev) is Circular (and usually encrypted except for a small handful of stations) and everything else is linear.... basically Echostars = Dishnetwork, Nimiq=Bev, and Spaceways (and maybe one or two echostars too?) = DirecTV. Dishnetwork and DirecTv have subscribers in United States. Bell Expressvu has subscribers in Canada.
There's also another network that encrypts called Globo something or the other? Can't remember the name... and they use linear, mostly on IA5, and there's a few others too, like the signals encrypted with Powervu... There's a lot of technical know how round here. Asking questions is good, but reading can be helpful too...
There's a lot of learning you can do by reading the FAQ sections.