"alanbobet", imdb user wrote something very interesting recently :)
http://www.imdb.com/title/tt1245112/board/nest/124721 218?p=1
"Mr. Plaza in the NY REC screening this past weekend, didn't reveal much about how REC 2 was being filmed, but he did state that the sequel will comence where the first one left off, that Manuela Velasco would do a cameo appearance as Angela Vidal in the sequel, that there would be more scenes outside the building as well as in the apartment building and that more would be revealed about the doctor and Tristana Medieros and the virus. So we'll all have to wait till late Spring 2009 for REC 2 to come out in theatres for the answers."