DraftSight for Linux is now official, as of 10:00 pm today. You can download the Linux (or OS X or Windows) versions from www.3ds.com/products/draftsight/free-cad-software/
Of course, if you were using ARES for Linux, then you would already be familiar with it. The diff: DraftSight is free -- free, as in free Linux -- while ARES is $995.00.
I've been using ARES for Linux (for the ebook I wrote about it: "Inside ARES for Linux"), and it is pretty much identical to the OS X and Windows versions -- both in terms of UI and operations. There are minor UI differences, which might be due more to the dialect of Linux I use (Mint Linux 8) -- just like it would look different on Windows XP than on 7.
Operationally, ARES for Linux is more like the OS X version, because only the Windows version supports things like OLE. Still, having OS choices is pretty exciting for an anti-proprietary guy like me.
I do, however, get the sinking feeling that the future of these CAD packages on Linux -- ARES, Bricscad, DraftSight -- is about a bright as Linux on netbook computers. (For a while, 95% of all netbooks ran Linux; today, 95% run Windows.) Maybe it won't be a problem, as long as CAD vendors are content with their Linux products staying at a 5% OS market share, or so.