What happens to Obama's senate seat?

Illinois' governor (a Democrat) will choose a replacement for the 2 remaining years in Obama's term. Somewhat similar answer for Joe Biden's Senate seat, except that in Biden's case there are the full 6 years remaining on his term (he was re-elected to the Senate the same day he was elected Vice President). The replacement senator will fill the first 2 years of the term, and then in 2010 a special election will be held to determine who fills the remaining 4 years.