An interesting article about development of low-cost airlines serving Portugal here:
http://www.centreforaviation.com/news/2009/08/24/low-cost-carrier-revolution-transforms-portugal/page1
Off particular interest is the following quote:
"One interesting development is that Ryanair is known to have sounded out the potential for operating from Porto to Cabo Verde (Cape Verde), the West African island nation that was a Portuguese dependency until the mid-1970s and which has become very popular with European tourists during the last five years."
Given Ryanair's increase in operations to the Canaries Islands this would make sense as Cape Verde is only a further 60 minutes flight and has much more potential for growth than the Canaries.
My thanks as always to Sergio Bastos at http://www.lowcostportugal.net for this information.