Autocorrect in iOS 4.3 now tracks two words as you type. For example, "lessvmistakes" becomes "less mistakes". This is a neat little addition that is so natural to use that I didn't even realise its presence. It does need a little work, though, as it just tried to autocorrect "autocorrect" to "author Rex". I'm not sure how I managed to trigger "undies IRS" earlier either, but it sure gave me a chuckle.