Hey Flax, I listed a computer piece on Craigslist recently and got a couple of the same emails. The followup was that the sender's assistant got the amount wrong, and sent payment to me that was scheduled for someone else (my name, their amount). It was kindly requested that I cash the money order, pocket my amount, and send them back the difference (after all, I am an honest man...right?). This is an updated scam. The money order is not legit but your bank will cash it and days later it will get rejected and they will deduct the money from your account. By then you will have sent the money to the scammer. FWIW, I have not actually received the money order yet. Either his assistant, or the post office, is slower than expected.
Don't walk, run...high dollar items on Craigslist seem to attract this scam nowadays.