Just had another read and it does say prior to the 1st so I am also claiming for my macro lens bought at the same time.
If, like me, you purchased your 40d before the cashback started on 1st Oct you may of been a bit disappointed, but I see you can still claim it.
See here and scroll to the very bottom of the page.
I bought my 40D on 22nd September and can confirm I have successfully claimed my Canon cash back. Payment was fairly quck too :)
Thanks Mick, I cut the label of the box went to the website and it still shows 1st Oct, can I still claim.
Just had another read and it does say prior to the 1st so I am also claiming for my macro lens bought at the same time.