scroft, a report on portugalresident(dot)com, dated 13 April '07 and titled "Algarve prepares for luxury tourism" shows that Monte Santo was originally a Hilton development with Imocom as the developer.
It stated: "As well as As Cascadas Resort and Spa, Hilton International has announced another two projects that are in the pipeline.
The Monte Santo Resort, in Carvoeiro, will have 67 Hilton Grand Vacations Club apartments and 54 tourist apartments. With a total investment of 55 million euros, the resort is due to open in May 2008."
My understanding is that Hilton pulled out due to a belated discovery that Portugese hotel regulations called for a set up different to what was planned at Monte Santo.
As a result, Imocon, the project's developer, went ahead with completion of the resort solo (to the planned Hilton standard )and Hilton have now got nothing to do with it.