Configuring only the code you need can bring the actual kernel size down to very small images. Configuring a kernel for a small embedded application takes time, but its well worth it. And fast.

Yeah, I was thinking the same. I wonder how many of those lines are really "kernel-for-real" essential code and how many are in various drivers.

It's nice to have choices. It's also nice to have most of those choices sitting on your hard drive unused, rather than being loaded into memory. It looks like that's still what's happening with Linux.

If it's too heavy, there's always TinyOS.

I think you are being a bit pessimistic here, what could possibly go wrong compiling a vanilla kernel? :P