Seeking Grammar Police Ruling - Typo's

[Steve]

Got into a discussion at Orson Scott Card's Hatrack forums.
We were discussing a completely different subject and at the
bottom of my post, I added that I was going to go back and fix
the "typo's" in my previous post.

Well that certainly opened a can of worms. Some one made a cute
comment about biting their tongue over my use of "typo's". I 
then inquire as to why they were 'biting there tongue', and
that started a long debate over whether "typo's" was indeed
correct or not.

They, the others in the discussion, insisted that 'typos' was
the correct plural of 'typo'. I never really disputed that,
but insisted that "typo's" was a valid contraction of 
'typographical errors'. 

Now, without a doubt, 'typos' is the more common usage by a
wide margin, but it being common doesn't make me wrong.

Anyone care to weigh in on whether "typo's" is or is not a
valid contraction of 'typographical errors'? ...Carol?

Sorry...it's just one of those things I can't let go of. 

steve/bboyminn