I just finished watching the final episode of House Season 4 a few minutes ago. This season, the ending is not a cliffhanger. It's rather sad in fact.... If you want to know, you can get spoilers through the Net.
I just checked the Net and it appears they're already filming Season 5. This time around, they've started filming immediately instead of the customary break in between seasons.
Although season 4 ends without a cliffhanger, I still can't wait for season 5 to begin airing....But before that, I've got to catch up on Prison Break which was also affected by the writers' strike and has now resumed!