I'm in no way surprised by the results of the poll; I wasn't sure which way we would vote (although voting to merge seemed likely), but I was quite certain they would vote not to merge, and I was actually shocked they had as many Yes votes as they did.
In my experience, if you ask Gentoo/Arch/Fedora/etc. users what OS they use they'll say "Linux", and if you ask Ubuntu users they'll say "Ubuntu". Unfortunately, the same is true when it comes to searching for problems. If I'm trying to figure out how to do foo, I'll google "linux foo" -- Ubuntu users will google "ubuntu foo", even if foo is completely distro agnostic. The reason (and I'm not trying to insult Ubuntu users, I suspect they would say the same thing) is Ubuntu users tend to be new to Linux and simply don't know which parts are Ubuntu-specific and which aren't. This means they end up on the Ubuntu SE and ask their question there, and so far (not unexpectedly, since we're both in beta) it looks like they don't direct distro-agnostic questions to us -- the newest question on the Ubuntu side is about Rhythmbox's python interface; the one before that is about LVM, and before that is a generic partitioning question.
Rather unfortunately, the impression I got from the initial poll announcement comments was that the Ubuntu side was worried our side was too advanced and would be throwing command-line solutions at people when they would prefer a GUI solution. So far that doesn't seem to have been the case, and (as xenoterracide mentioned on that thread) we even dropped "advanced" from our description, but it's definitely a valid concern. More unfortunately, there wasn't much of an opportunity to actually discuss the merge and address concerns; I imagine most people found out about the poll from the notification on the sites, and voted without seeing any of the arguments at all.
I started out thinking the communities should stay separate but changed my mind pretty fast after reading the arguments; it's like saying C# and C++ should be separate and SO is foolish for merging them together. C# is the language most asked about on SO, and I know nothing about it, but the "Ignored Tags" feature is sufficient to let me completely ignore those questions. I think similarly tagging Ubuntu questions [ubuntu] here would work well.
I didn't realize until I made the link just now, but we actually have an [ubuntu] tag with 14 questions on it. Normally we've been told migration options won't be available until after a beta is finished, but if we're going to stay separate communities I think it would be highly useful for us to each have a migration option to the other's site now. There's no point in keeping the communities separate if we're not going to move questions that belong on each other's sites; we might as well just merge then. I'll talk to the SE team and see what they think