Hiya,
Yes my in laws have got these for our trip in December. There are about the same price as the 10 day pass but are valid for 30 days and come with a few extras like entry to KSC and Salvador Dali museum in St Pete's. Great value for money.
I thought I'd read somewhere that these weren't definitely being sold past spring 2005 but your trip may be before then, and in any case they may sell them after that date - but I think for now April / May is the latest you can get them for?
If you need any more info let me know!
Cheers
Karen