Linux-cr can do live migration - e.g. VDI, move the desktop - in
which case skype's sockets' network stacks are reconstructed,
transparently to both skype (local apps) and the peer (remote apps).
Then, at the destination host and skype continues to work.
That's a really cool thing to do, and it's definitely not part of what
DMTCP does. It might be possible to do userland live migration,
but it's definitely not part of our current scope. But if we're talking
about live migration, have you also looked at the work of
Andres Lagar Caviilla on SnowFlock?
http://andres.lagarcavilla.com/publications/LagarCavillaEurosys09.pdf
He does live migration of entire virtual machines, again with very
small delay. Of course, the issue for any type of live migration is that
if the rate of dirtying pages is very high (e.g. HPC), then there is
still a delay or slow response, due to page faults to a remote host.