Actually, the input queue feature is not a kernel issue. It's a Presentation Manager issue. The PM was designed to use a synchronous input queue for two reasons; one, it's much more efficient on system resources, and it permits some interesting features. There used to be a universal spell checker for OS/2, though I don't remember the name. Since the input queue is synchronous, it's easy for an application to hook into it. So, what the universal spell checker does is scan and spell check all input from the keyboard. It had a control key combo to toggle checking on and off. You could buy this one spell check and never need one for an application ever again.

WRT kernel tech; OS/2's kernel kicks linux's ass when it comes to threading. It is the best threading kernel I've seen, though I've not played with BeOS, which I hear is very good. However, it's not portable like the linux kernel is; it's got lots of x86 assembler I hear, and other fun things like that, so you can't take it to another platform very easily. However, when it comes to raw performance, I'll take my native threaded servers over the unix stuff any day of the week. They really get a lot more work done....

That said, a well implemented OS/2-*nix hybrid would really catch my attention...