I'm so sorry, I was incorrect. I briefly owned a Nexus S which had an unlocked bootloader. I currently own a Motorola Photon, and even though there are ways to flash the bootloader, doing so cripples 4g (I believe this is by design).
Most of the non-Nexus phones technically have a locked bootloader, so that people can only run firmware signed by the carrier. In practice, there are ways of jailbreaking the vast majority of locked phones, but there are some people who don't want to void their warranty or don't want to use community ROMs.
AFAIK (and some google searching seems to confirm) the Galaxy SII does not have a locked bootloader. I believe that the original Galaxy S was also unlocked.
So which Samsung Android devices have locked bootloaders?
Motorola and HTC tend to lock their bootloaders more often (though this situation is improving).
It's using 4.0 APIs, according to Matt Seigler's story and interview with Google SVP of Chrome Sundar Pichai:
"Back to the bad news: some of the more advanced features of Chrome for Android require APIs found only in Ice Cream Sandwich, so the team made the call to make it only available for Android 4.0 and beyond. Again, this means only 1% of current Android users out there can actually get and use the browser right now."
- http://parislemon.com/post/17215781807/chrome-for-android-th...
1% of Android users is still at least a couple million. That's more than enough to get a reasonable pool of beta testers. By the time it gets out of beta, the Android release distribution will probably look quite different.
