I'm also in Madison and I haven't gotten a letter yet, even though I just got my bill.
I talked to a lady at corporate CS today, and she said 16 meg would be here around the first of the year. She also said that the price of my 10 meg would DROP by $10. Making my current (pre-tax) monthly bill of $139.96 drop to $129.96 when 16 meg comes to town.