Yawn. Thune has a cookie-cutter neoconservative voting record. He's a party-line ideologue who brings nothing new to the country whatsoever.
Thune would be vulnerable in November if Obama regains popularity. He barely beat om Daschle in 2004, a good year for Republican candidates. To have any viability as a Republican nominee as either President or Vice-President in 2012 he must win re-election in 2010. He is an obvious target for the Democratic Senate campaign in 2010.
Even if the Dems gained signficant popularity, which is possible, Thune will not at all be vulnerable. He beat the Senate Minority Leader in the last election, and Daschle was very highly regarded in SD, despite being a Dem.