CBS’s David Letterman has a high profile guest this week – Democratic Presidential candidate Barack Obama (D-IL) will appear on his show Wednesday 9/10/08. But Obama’s been seen many times in many places. So maybe Charles Gibson’s scoring an interview with Republican VP candidate Sarah Palin (R-AK) is the bigger piece of news. In fact, it’ll be Obama’s fifth time on “The Late Show with David Letterman” dating back to post-election 2004. It is unknown when the interview of Palin by ABC News anchor Gibson will be ready for public consumption: he is expected to conduct multiple interviews with Palin later this week.