El Pais is reporting that Keanu Reeves is in Montevideo, Uruguay to attend a wedding. He arrived at noon and is staying at the Hotel Sofitel Montevideo Casino Carrasco.
The info is from here.
Note: I am assuming he is attending the wedding of Gabriela Roses and Carl Rinsch.
Update: The El Observador has posted an article confirming that Keanu is in Uruguay to attend Rinsch’s wedding.