Out of the blue, a Chinese hacker called "Chomper" has released an 80MB .ipk file that includes a port of Android that can be launched from inside WebOS! It seems to be a somewhat unstable port that defaults to Chinese, but you can change the language to English. I wouldn't recommend installing it in its current state yet, but it does look like an interesting project.
Technically, it's quite clever - it shuts down the webOS Luna interface and then execs Android from a chrooted filing system, which explains why it only takes 10 seconds to launch. There is the issue of actually returning back to webOS after an Android shutdown (or hang) though - at the moment it requires a full reboot to do that - but I expect that could be fixed in the future.
Personally, I think I prefer the CyangenMod dual boot concept because the Chinese port requires you to launch webOS first (70 seconds from cold...ugh) before firing up the Android app (another 10 secs), whereas Cyagenmod gets you into Android in half the time and doesn't need a working webOS install either (and no doubt the eventual option of wiping webOS completely).
If you really must install it, I'd advise you to check out this video before you start.