Found this note on one registrar's site:

Registrar changes
We are experiencing problems when customers
want to transfer their domain from NSI or
register.com to joker.com (and others).

Those 2 registrars changed their policy in so far
that they ask the owner of the domain additionally
for confirmation. That would be acceptable, but we
made the experience that
- the verification email asking for confirmation is
formulated in a way which can mislead to a wrong
answer. Be careful when answering!
- It happens that even confirming the transfer, the
registrar denies it.
That behavior has been discussed between all
ICANN accredited registrars. All but the 2 agreed
that this is bad practice. We can not anticipate
when they return to a more user-friendly policy,
probably only when they find that customers
do not support it.

All we can recommend is :
- read carefully the verification-email
- in case they do not follow your request send an
email to them and to ICANN explaining the case.

it's so true though. The most common problem I have with new hosting clients is domain transfers, and most are with a certain problem w/ a certain registrar.

AH

That problem is currently being addressed with the DNSO, http://www.dnso.org, and ICANN, http://www.icann.org. I would imagine we should see some policy changes within the next month.