I heard an episode about this a while back and they didn't have a good term for this. I've been dying to post this so I'm glad I discovered there's a forum.
When autocorrect changes something to say the wrong thing, it's called auto-incorrect. I thought this was a pretty obvious term but no one seems to realize it until I point it out to them then they get it. I coined this term before the episode even began, but that's what it is, don't you think?
Love you guys!
So,I think we'd better say,looking from a higher view, that it's 'auto-suggester' that just wants to say sth: "Hey! I am here."
I like auto-incorrect as a description for what's supposed to be auto-correct. The spell-check module on most systems is driven by your word processor. It uses a dictionary that's obviously incomplete, especially when it comes to technical terms. Its corrections are often wrong, and sometimes humorous.
See: http://marcbabineau.hubpages.com/hub/Spell-Check-Mistakes for some great examples.
If you turn off auto-correct (as I have on my system) you get auto-suggest by default, at least in Windows. Since I do mostly tech writing, I find myself using the "add to dictionary" option quite often.
FYI: It's possible to "un-add" a word by manually editing the custom.dic file. At least that's the way it works with MS Word.