This may be a clue: Only my first Skype contact appears in Adium, but his status line in the Contact List shows a comma and the name of the second contact". e.g.:

[My Friends]
Aaron
I'm away from my computer
Betty
I love Mondays!

[Skype]
Chris
,David

Adium 1.3.5, Skype 2.8.0.659.