And that's because Samsung has yet to release the actual source that the kernel is built from. So essentially, we have a single, prebuilt kernel. For the devs to build their custom kernels, they need the source, not a prebuilt kernel.
So, in a bit of twisted irony, while we now have 2.2, we're still beholden to Verizon and Samsung officially releasing it (and it's source) before we can get all the optimized kernels.