Yes; the plural of '(computer) mouse' is now established as 'mice'. But,
when these gadgets first appeared, there was uncertainty, and both 'mice'
and 'mouses' were used for a while, before 'mice' won out.
You are right, though, that 'mice' seems odd. The person who has worked on
formations of this kind is the psycholinguist Steven Pinker. Pinker has
drawn attention the observation that irregular forms often become
regularized when they undergo certain kinds of shifts. For example, the
verb 'fly' has past tense 'flew', but the verb has given rise in baseball
terminology to a noun 'fly' (as in 'He hit a fly to left field'), and this
noun has in turn given rise to a new verb 'fly', which is regular: 'He
flied out to left field', not *'He flew out to left field'.
I regret that I can't provide the reference to Pinker's paper. I've
recently moved office, and that paper is in a pile that I haven't sorted
yet.
Larry Trask
COGS
University of Sussex
Brighton BN1 9QH
UK
larryt@cogs.susx.ac.uk