Rum usually is produced from sugar cane, a product not grown in Portugal.
The most popular run-type spirit consumed in Portugal Cachaça from Brazil;
As alternatives I can recommend the locally produced Portuguese Air Force (FAP) environmentally friendly jet fuel substitute know as Medronho.
One should be aware that only the highest quality non-commercial product produced in secretive stills in the Area 51 type region in the Monchique area of the Algarve and the neighbouring southern part of the Alentejo is worth consuming! One should watch out for the protective Portuguese version of the Men in Black if driving around these areas! They usually wear Tommy-Lee Jones type Raybans and drive Green Painted 4 x 4's, with GMR painted on the vehciles! (Guarda Medronho Republicana). If you try to get near any of these stills, they will usually shoot first and ask questions later!
A similiar product produced further to the north in Portugal is "Bagaceira"!
See (in Portuguese): http://pt.wikipedia.org/wiki/Bagaceira
Like Medronho, one should only consume the the highest quality non-commercial product!
