Electoral votes: 3
2004 result: Bush 60%, Kerry 38%
2000 result: Bush 60%, Gore 38%
Most recent Democratic win (1964): Johnson 56%, Goldwater 44%
African American percentage: 0.9% (national average is 12.8%)
Link to polls in Real Clear Politics
McCain has a healthy lead in the most recent of those polls. This is another state in which I would expect Sarah Palin to play well, so it's not surprising that their ticket seems to have achieved an above-average post-convention bounce in South Dakota.
Even favorite-son George McGovern could not carry this state for the Democrats, when he headed that party's ticket in 1972. It looks pretty safe, but not completely safe, for McCain.