According to the Belgian online newspaper, Knack.be, T.M.s King Albert II and Queen Paola of Belgium will attend the beatification of the late Pope John Paul II on May 1, 2011. Also, T.R.H.s Prince Felipe and Princess Letizia of Asturias will attend on behalf of the Spanish royal family, according to the newspaper, Rome Reports.
It is unknown at this time if other members of various royal and princely houses will attend, such as Luxembourg and Monaco, but I have a feeling the latter two houses will confirm in the next few days so stay tuned.
To view a video report regarding the royal attendance please click the link: Video
For more information about the beatification of the late Pope John Paul II please click the links here and here.
Source: Rome Repors and Knack.be