Almost the same thing, but did some digging around.
It all started when I've seen abracadabra in LJ instead of cyrillic
characters in tags. I managed to fix that by removing the utf8_encode
() calls everywhere where taglist was concerned. And the trouble went
away. Same thing was with the post title - it crossposts ok.
The problem, as I see it that utf8_encode tries to encode a string
that is already in UTF for the second time - it workd well with
Western alphabet, but doesn't with cyrillics (and probably any other).
But for now I can't tackle the post's body problem: there's no
abracadabra there - the symbols are simply not shown in LJ. Tried to
remove utf8_encode() from $the_event, didn't work.
Thanks for any ideas/updates!