I dont get the hype. BSD and Solaris have had proper containers for years now. Just because Linux hasn't had any all these years and LXC is maturing only now, it is wrong to think that containers are the next big thing.
I also think it's strange. FreeBSD jails are essentially the same thing. When I describe Docker, I would call it "FreeBSD jails for Linux" rather than "lightweight virtual machine" or even "iPhone apps-style isolation".
But I do get the hype. BSD and Solaris, although they have many interesting benefits, just aren't that popular for a variety of reasons. I won't turn this into a discussion of why they aren't popular, but it's a fact that Linux is much more popular. Most people aren't going to switch even if BSD and Solaris provide more benefits. But now that an important feature has become available for Linux, I can see why people get excited.
It's like Node.js. Servers with evented I/O has exited for years, if not decades. But the fact that Node.js is Javascript made it mainstream and that's why there's hype.
Actually the Linux "container" implementation (namespacing) is based on Plan 9, and is much more modular than FreeBSD jails. Not that lxs/docker use that, just use as a jail...
Not in stock Linux - OpenVZ has been a bit like Xen that way, requiring a custom kernel. Which for most people means a dedicated host machine is needed.
