As well as Moyles on xmas day, theres a Chappers and Dave football review program special going out on Boxing Day at 10am. (Not 100% sure if thats 5 Live or Radio 1 mind). Christmas day is basically a load of specials including Coxy, Jo Whiley and Moyles.
On a related note, for a week following Christmas, (Boxing day onwards), the R1 schedule changes pretty drasticly. Emma B's doing Breakfast, Colin Murray fills in for Jo Whiley and I *think* it was Nemone doing 1-3/4 then Wes following on from her. Oh yeah, Vicky Marsdens doing the early breakfast then too, if anyone cares. Scott Mills is doing the New Years eve countdown from 8 too.
(not entirely sure why I posted that there, but it seemed the only place to post it that really made sense).