Here's the information posted on our Cuba information page
http://free-esl.com/teachers/cnotes/display.asp?fIndex=11
Finding Work
With the state of the economy, preference for jobs is given to Cubans so a foreigner will be well down in the pecking order. There's the possibility of working for nothing, but as there are quite a number of qualified Cuban English speakers competition for paid jobs is high.
One possibility is going to Cuba with a volunteer organisation who can arrange the job and placement. One possibly worth contacting is Grupo de Especialistas en Lenga Inglesa.
Conditions
Pay is poor by Western standards from about 20 to a maximum of 200 USD per month. This high figure is what local high earners are on so it's unlikely to be at that end of the scale and more likely to be about 30-40.
Schools vary. Some have computers and tape recorders but most in the state sector have much more limited resources. It's hot and sticky in the afternoon (no air conditioning).
Government
Be circumspect. And especially so if you have an agenda (promoting anything but the government line or spreading religion) as the chances are you'll be found out and deported.
However, Castro has expressed the desire for Cuba to become bilingual (English & Spanish) so there is a demand for trained teachers.