According to The Pittsburgh Post-Gazette, there's a major event to come on The Ghost Whisperer.
For starters, the article states that many behind the show had wanted to wait until after November sweeps to kill off Jim because it wasn't clear how to sustain the tension of the relationship between Melinda and her new neighbor, Sam (whose body the spirit of Jim has taken up residence in).
However, those that wanted to take a risk with the story line won out in the end. This ought to explain any dragging out of the relationship, as the series is treading water a bit.
But that won't last long.
Look for The Ghost Whisperer season to culminate in a wedding between Melinda and Sam.