1. Both parents are speech pathologists.
2. They read to her a lot.
3. They taught her sign language.

There's history of teaching kids sign language when they are infants/toddlers, like before they learn how to talk or if they have hearing problems. So, it's no surprise that these techniques, applied to a healthy child, helped make her proficient at reading.

My boyfriend could read by 2 years of age. He's more than fine now; in fact, he's the smartest person I know!

My oldest girl could barely pick her nose and walk at the same time when she was a year and a half. Now she's doing her post-doc studies at UT-IMCB.

Very Classy.
I'm sure Edward R. Murrow would be proud.

Everyone has his or her own talents. Early reading is just one. Maybe it'll all even out in the long run (the rabbit doesn't win the race, after all) -- and unless a good reader is motivated to put his or her brainpower to good use, it's nothing more than a parlor trick. (That's why we treated my daughter's skills as commonplace -- she went to preschool thinking reading and math were things every three year old could do.)

Obviously infant humans have tremendous unacknowledged skills as semioticians. Perhaps watching the signing show at such a very young age simply developed her strengths in interpretation of signs that much faster. At what age did she begin to view the program?

For Elizabeth, personally, the struggle will be for her to develop knowledge of what the words (both as spoken and written) are referring to. She obviously has mastered the phonics of the process called reading, which is understanding the sounds that the combinations of written vowels and consonants.

As a matter of human study, though, I wonder who will be setting up a child study lab that trains pre-toddlers to associate sounds and gestures with letters?

As an example -- I know the basic rules of pronounciation in German. So, you could hand me a paragraph written in German and I can read and pronounce it more or less correctly. There will probably be a bunch of words therein that I'll not know the meanings of, though. I'm wondering how big her working vocabilary is... Neat story in any event.