They do not recognize St Gregory of Palamas. Actually they reject the Essence and Energies understanding of God and refer to it as Palamism. I am quite proud to be a Palamist myself however.
The biggest (and yet most ignored) difference between Orthodox and Roman theology is the difference the teachings of Palamas and Valaam. There is no one more un-Roman Catholic than St Gregory Palamas! (God willing I'll be venerating his relics when I go to Thessaloniki this week! )
eh, that's what I get for not double checking wikipedia
Though he is not widely venerated in the Roman Catholic Church he is recognised as a saint; Palamas is liturgically commemorated by the Melkite Greek Catholic, and Eastern Churches, who are in communion with Rome.