First post so be gentle :)
Got an email about this and I think the offer is open to anyone.
"On October 10, we're celebrating 10 years of Bejeweled, and we got you a little something."
Follow the deal and this will take you to the PC version of the game. If you wish a different version then scroll to the bottom and on the left there will be other versions available to you.
Then simply click on "Get it Free" and the code "BEJ101010" Should be entered automatically and you should be able to download it for free.
Today only as far as I know, so get it quick!