My 2006 3.9 seems to be leaking oil into my coolant...is this a huge problem and is it common on these cars?

 

It's not an immediate threat, but I wouldn't be driving around too long without getting it fixed then flushing out your coolant. A week at most. It's fairly common in earlier year Monte's because of the old gasket style that GM used - but not as common in the 06-07s because the gaskets switched over to aluminum.