If you're not new to the HTC EVO root world, then you've probably heard of Ziggy's kernels. His dual-core mods have been incorporporated in other kernels recently and he's now back on the scene with a Gingerbread/Sense kernel with very little documentation or features list that I can find.
While I generally do not download/install/run kernels that have no features listed, it's a Ziggy kernel posted by Ziggy471 himself, so it had to be done.
This kernel appears to support dual-core all the time and to be running a good 100-200mAh lighter drain on my battery (or about a 30% juice savings right off the bat from the stock kernel).
I say "appears" because evidently if you flash one of Ziggy's previous dual-core kernels you're set up for dual-core from there on out. I'm pretty sure I was on single-core stock, but am a bit uncertain at the moment. I also say "appears" because there's been a lot of tower work in my neighborhood and that lower juice consumption could simply be that my closest cell tower back online.
I don't see all that much improvement over stock in execution or IO, and quadrant scores aren't all that much to write home about, but that's also not running overclocked.
For whatever reason, Flash Image GUI refuses to flash this kernel, but you can flash it from fastboot if you're so inclined/stuck on HBOOT 1.50 or regular recovery if you have S-OFF.
I've flashed this kernel twice to test it out, and it has some pretty interesting tangles with Warm TwoPointThree on initial boot; both times my home screens were lost after the first boot. The first time, a reboot brought them back. The second time I rebooted and then had to clear dalvik and cache and reboot again to get the home screens back. In both cases I had cleared dalvik and cache before flashing the kernel, so something minor is afoot.
This kernel doesn't seem to be a cheetah or a turtle. It seems to work with a few initial dalvik-based hiccups immediately after an install and appears to be quite stable. It's been out for about a week and a half now, and the worst anyone seems to have to say about it is it doesn't play well with some installs of Synergy ROM. Your mileage, of course, may vary.
If you're so inclined, try it out after making a Nandroid backup. Let us know how it works for you. And if you manage to wrench a changelog out of Ziggy's hands, then feel free to post it in the comments.[xda-developers]