There are four at this point, six if you count B units, plus the covered hopper; Alco PA1 and PB1, EMD late F3A and F3B or early F7A and F7B, GE 44-Ton, and a small switcher.
Peter pointed out that you had included a thumbnail in your post. My browser doesn’t follow those links for some reason (security settings I suppose). I grabbed it from the page code and will work from there.
I’ll be concentrating on adding passenger wagons for the locos I’ve already added. I may add a couple more textures for the covered hopper, too. I’ll look at adding more locos after the release of v1.4.