GSM World is a great resource, but companies don't always update it as much as or as quickly as they should.

Cubacel.cu seems to suggest that they do have data. Look at the "transmision de datos" page. It doesn't look cheap, but it is there. Roadpost.com used to work there, but stopped coverage because Cuba's net isn't 100% reliable. Too many people complained so now it is 0% rather than 80% coverage. Cellhire also doesn't offer service.

If I were you, borrow a GSM Treo or equivalent and get a prepaid SIM down there. I would set the phone to poll my mail every hour or manually. I'd also bring a travel router or something down and try to check my e-mail as much as possible off of hotel wifi.

PS: One strange thing I learned from my Blackberry days. If a country has data roaming with your home country, it doesn't matter whether the country which is being visited actually supports Blackberry. You essential have a data tunnel to your home network and on to the Blackberry server. I had Blackberry coverage in the UAE long before the country rolled out Blackberry service because of this. I basically milked an international Blackberry plan to the breaking point.