To premise my question, understand that I have been (and intend to continue to be) active on MO, and have not yet started to learn how the rest of SE 2.0 works.
The meta.MO question migration versus on-hold reminded me that I don't quite know how migration works. I probably should learn, since I do often vote towards closing (or sometimes towards leaving open) questions on MO. Often "this question belongs on Math.SE" is an option. What happens if I click it (and, presumably, enough other people do too)? Does the question immediately move to M.SE? Often, the questions that I vote to close are not in their present forms appropriate for M.SE — if the question immediately moves as an "open" question to M.SE, then I will henceforth stop clicking the "migrate" button.
I assumed, but migration versus on-hold suggests that this assumption is wrong, that when I clicked "close because this question belongs on another SE site" that the message that the question belongs somewhere else was sent to the OP, and meanwhile the question was sent to some sort of queue at M.SE, where high-reputation users could comment on it and decide whether it really is appropriate.
The same worry applies to migrating to other sites. I occasionally see questions about statistics, but I am sufficiently far from being an expert in statistics that I can't tell, really, whether they'd make good stats.SE questions. I'd be much happier if migrated questions enter some queue in which they are reviewed by experts from the other site, rather than being dumped there.