Oh neat. I always considered it the prelude to the actual solo (i.e. the classic Bjorn guitar wankery). In this case, yeah, Zombie Inc would make my Official List.
I tend to discount guest solos on the basis they don't play those solos (or often even those songs) live. They had quite a few guest solos in the early years - I guess because Jesper & Bjorn weren't comfortable doing them? I wish they'd have done that on SC and Battles as Bjorn was running on empty and created about 20 solos that almost all sounded identical and pointless.