I just happened to wander over to the No Limits site to see if an update had been written for Mac yet, and to my suprise it was released yesterday. I know there is a No Limits forum and Coasterbuzz Games section, but it doesn't seem like they're that heavily traveled and that's why I posted it here.
It contains all the features of the PC design, including new train designs, and new tracks. The only thing it doesn't include from the PC version is German-language support. After seeing my friends 1.6 version for the PC, the smooth feature is something I could definitely take advantage of.
The only bad thing is that it involves a full upgrade, which still isn't bad at $29.95. I know there was some grumbling about that when the PC version was released, but my friend mentioned that he was sent a 1/2-price coupon from Mad Data. Did anyone else get this coupon?