There are discussions of SU on Linux here
http://www.sketchucation.com/forums/scf/viewtopic.php?f=15&t=11412
and
SU and Rubies on Linux here:
http://www.sketchucation.com/forums/scf/viewtopic.php?f=180&t=9687
The latter includes a discussion on dos2unix, which is used to convert Rubies (RB format; RBS format seem to generally work without conversion) so that they are correctly interpreted in a *nix text environment.
I should add that Rubies that depend on unusual Windows dlls or other applications might not work. For instance, commercial rendering plugins like VRay will probably not work at all. However, to simply run SketchUp on WINE most of the Registry tweaks no longer seem to be needed, assuming you have up-to-date versions of WINE (from WINEhq) and your distro...and a decent modern NVidia card.
I spoke to some of the SketchUp team at 3DBC about a native version of SU on Linux, and their reply was that they were really just a very small portion of Google and that they simply did not have the manpower/budget to produce and maintain a port (or multiple ports, given that they might have to create versions for different distros).
By the way,
@unknownuser said:
There is a Mac OS version and as far as i know OSX and Linux are both unix based...
is not quite correct. Max Os X utilizes the Darwinkernel, a derivative of FreeBSD, which itself is a descendant of BSD (a version of UNIX modified to avoid copyrighted AT&T-created code). Linux (full name: GNU/Linux) is a Unix-like system made from Richard Stallman's GNU Project's utilities with a kernel written by Linus Torvalds. The two operating systems are only outwardly similar by intention...if BSD hadn't been caught up in a delaying lawsuit by AT&T, Linus wouldn't have needed to develop the Linux kernel. Wikipedia has long, esoteric discussions on all these topics. The upshot is that you would be more likely to get something written for a Mac to run on FreeBSD (or vice versa) than on Linux.