The following Mudcatters have threatened to show up so far (in no particular order):

Jeri
Animaterra
Bat Goddess
Curmudgeon
Woodchucks (however many an "infestation is")
Naemanson
Catrin
John Nolan
Uncle Jacue
Susan A-R
Kendall
Sinsull
CamiSu
Kelticgrasshopper
Peg

...and there's a good bet Barry Finn and Ewan McVicar will be there.