I'm not sure that this is completely the same, but when node.js was introduced it provided a server-side programming language that a ton of web developers were familiar with.

Swift is doing something similar now that it's open source there is a huge community of iOS (and to a smaller extent Mac) developers who are excited that they can code on other platforms (or will be able to in the near future) using a language they already know and love.

Honest question: how common are non-GUI Objective-C apps? So far as I know, Objective-C has been available outside of Cocoa for a long time, but you never hear of people using it for non-Mac/iOS apps.

Is Swift different in this regard? Is more of the standard library open in Swift vs. in Obj-C? Any reason to expect it's non-Apple uptake will be better than Obj-C?

Objective C was poorly supported outside of the Apple ecosystem. Plus Objective C as a language hasn't been all that preferable to most developers. There was basically no reason to use Objective C at all outside of iOS and Mac development.

Swift, on the other hand, will now have full Apple support on Linux, and is a much nicer, and potentially more useful language. I think that with some effort on the community's part, it could become a serious contender for server side development.

I tend to agree. I've been using Swift off and on pretty much since its inception, and I like it well enough that I'd consider it for server-side stuff once the ecosystem's worth anything. My hope is that it brings a little sanity to things by presenting a sufficiently trendy alternative to Golang so I can deal with that a little less often (but that's only hoping).

Coming from some recent experience with Node/JS stuff, it lets you directly re-use some code (namely, data models and code that interfaces directly with them) on both the client and the server. It makes life a lot nicer.

Also, OSX isn't used as a server OS for good reason. Swift on Linux means that you can run that shared code in an environment designed around servers.