The last time I edited my profile (around 2011-09-26 22:00) and the next-to-last time (a couple of weeks before), I edited it on Stack Overflow and clicked on “Copy Profile to all Stack Exchange network accounts”.
The change seemed to propagate instantly to all main sites, but even now, on most meta sites, my profile is an old version that doesn't have an “about me” section (SU Meta, TCS Meta, Literature Meta, …). My profile on Linguistics Meta, has an “about me” section, but it's the version before from yesterday. As far as I can tell, this is consistent with each meta profile having been imported from the main site when it was created, and never modified since. There's one exception: my SF&F Meta profile is the version from a couple of weeks ago. (Also, my French Meta profile is in synch with the main site profile, which is a custom one.)
As far as I understand, meta profiles are supposed to be automatically imported from the corresponding main site. This doesn't seem to be happening (even allowing a few days for some cache to be updated).