I did not know that the US has only had a full diplomatic relationship with the Vatican for only 24 years, until I read a great Washington Post article describing the current and likely future relationships between us. According to the article, the US-Vatican relationship has never been "closer or warmer" than under the current Bush Administration, as the Pope agreed with Bush on many religious issues, only disagreeing on the invasion of Iraq.
This relationship is likely to change under the Obama Administration as, needless to say, President-elect Obama and Benedict XVI will have several differences of opinion. Watch for US Catholic leaders to apply pressure on Obama over his stances on abortion and stem-cell research, among others. At the same time, the Vatican will want a positive relationship with Obama to help promote international peace and the safety of Christians throughout the world. In this good cop/bad cop approach to the Administration, the Pope, naturally, will be "above the fray."