If you are asked to engage in a transaction via Moneybookers (moneybookers.com) - don't panic immediately - they seem to be legitimate, although I have never used them personally.
However, a friend of mine in Spain was asked to perform an escrow transaction through them, and to transfer money via Western Union.
This rang a couple of alarm bells, so I gave them a ring for him (my english is better, and the only phone number available was a UK line).
They confirmed that they do not work with Western Union in any capacity. I wouldn't normally pass on scam warnings, etc, however, this one was very credible and almost fooled us both - so beware!
If you do encounter anything like this, please forward related correspondence to firstname.lastname@example.org.