Justin is incredible. not only will Reaper have notation soon, but it looks like it may have native Linux capability by years's end. Is there another developer doing this kind of work? 
http://forum.cockos.com/showthread.php?t=8

Mixbus is on Linux, Mac and Windows.
 
Granted on Linux it's a hoop jumper to get VSTs to work, but hey if that's your thing, go for it.

Most devs aren't that interested in Linux support because it isn't an efficient use of their resources. Linux accounts for a tiny, tiny fraction of desktops, very few plugins/synths work on Linux, and it's media support is rather a mess. As such they don't feel it justifies the time. Only so much resources, you have to decide where to spend them, and for most pro audio software Linux isn't an area they feel would be efficient.

The new Steam Machines use a "version" of Linux. They have the clout of Valve behind those machines. And they still can't get "better" performance from this "lean" OS because video drivers (read: Media) aren't as good on Linux as they are on Windows. What makes anyone think that audio interface drivers (read: Media) are gonna fare any better?
 
Then as Bapu points out, the VST's that we all use will need to be ported/rewrote at the very least.
 
I just don't see any Linux DAW making headway (in the section of the market that we here on this forum occupy) anytime soon.
 
Eventually if enough users demand it over MS Windows/Apple OS it could gain traction. I just don't see that happening anytime soon. Hell I thought that it would have done much better in the gaming industry than it has. Back in second half of 90's  I really thought that by now it would be a major player. But it just isn't. And lack of great driver support is the major hurdle.

At this point there's too much fragmentation in the Linux market. The various factions who work on development can't agree as to what they'd want out of a real unified Linux desktop. So it remains amazing for embedded devices, good for servers, and extremely "meh" for desktop use. The groups that are actually unified in vision and execution with regards to Linux are ones behind the server/embedded roles.
 
Also there's simply the issue that Windows is "good enough". History is full of "good enough" solutions. Something gets to a state where it works well enough and everyone starts using it, and then it continues on inertia. Everyone uses it because everyone uses it and it is "good enough" so nobody is that interested in finding something different because that'd be difficult, and incompatible, and require re-learning and so on.

Chicken/Egg
 
One Day, enough people will have cobbled together sufficiently performing Linux machines to make them a viable option.  It may not matter much now, but 5 years from now it may make a ton of difference.
 
This move by Reaper will end up being called either "an incredible waste of resources" or "a truly visionary bit of leadership".  Risk, reward ...

BobF
One Day, enough people will have cobbled together sufficiently performing Linux machines to make them a viable option.  

You ought to make that a signature quote - that's a good one. 

BobF
 
One Day, enough people will have cobbled together sufficiently performing Linux machines to make them a viable option.  It may not matter much now, but 5 years from now it may make a ton of difference.
 

 
This is what I was referring to. I thought this same thing almost twenty years ago!! Sycraft gave more reasons why I just don't see it happening.
 
I do see it coming up and being used in specialized situations.

Considering that Justin has developed a notation editor in just a few months from scratch - when Cakewalk says it can't fix theirs because "the code is too old" - I wouldn't count this guy out. They also said we would never fly...

Grem

BobF
 
One Day, enough people will have cobbled together sufficiently performing Linux machines to make them a viable option.  It may not matter much now, but 5 years from now it may make a ton of difference.
 

 
This is what I was referring to. I thought this same thing almost twenty years ago!! Sycraft gave more reasons why I just don't see it happening.
 
I do see it coming up and being used in specialized situations.

I remember when Linux first started it's spread.  It was a college kid's toy, not getting much respect from "real Unix" folks - myself included.
 
Today you'd be hard pressed to find a data center that isn't using for some serious applications.
 
It probably won't be next year though