There was a great story on NPR today about some of the Hart and Risley's published research from the mid 90's concerning linguistic interactions between parents and children. You can hear or read it HERE. One of their significant findings was that by the age of four, children of middle and upper class parents (who have jobs considered professional) hear around forty-eight million utterances of words. But four year olds of parents who have received Aid to Families with Dependent Children have only on average heard around thirteen million word utterances.
Subsequent research: (1) shows there to be just as significant a gap in exposure to number of distinct words (as opposed to utterance tokens), (2) shows there to be just as significant a gap in exposure to assertions versus mere imperatives (talking to kids as opposed to just talking at them), and (3) suggests that this word gap is more predictive towards subsequent success in school than economic class in a variety of ways.
I'd be interested if people assessing arguments for various innateness hypotheses and perhaps claims about how these hypotheses should inform syntactic structure (over and above just getting distributional data right, which Chomsky describes as thinking of syntax as a mere "E-Languge" and not really linguistics) have taken up this data yet. I mean there's a lot of information now about how hearing more words, having more assertions directed at you, and hearing more utterances affect the abiltiy to master language related skills down the road. Also, the numbers might be relevant to determining how many inputs a connectionist system should be allowed before expecting it to converge on behavior that can be described with generative rules (I have no idea where these kinds of debates are at today).
At the very least, Pinker's analogy between learning a language and learning to walk in The Language Instinct now looks incredibly strained. However, one should not confuse the mere issue of innateness with the extent to which innateness claims (if true) actually do constrain syntax the way most proponents of Government and Binding or Minimalism take them too; for example, despite his continuing commitment to strong forms of innateness, Pinker (in common, and with equal cause for surprise as Jackendoff and Cullicover) is actually now a pretty severe critic of some core Chomskyan claims.
In any case the happy news in the story is that programs have been set up to help parents communictate better with children and they are showing some success. This is a really nice instance of social science research having the capacity to make a positive difference to education in the broad sense.