I've always suspected tha part of the reason American politics is so incredibly partisan is precisely becuase the american constitution renders its institutions impotent unless they work together. This may have even been the intended effect, seeing as some seemed to believe that the less government going on the better.
While logically all the US institutions should compromise and work together to achieve what's necessary, the way they're all given overlapping powers and areas of responsibility whilst simultaneously being absolutely safe (their power can't be diminished even if the others gang up on them for being a dick) means the entrenched conflict is pretty much inevietable.
The Australian system is pretty different. Its pretty close to the UK system because in a Parliamentary system the parties themselves are more likely to compromise with each other but there are fewer MPs who are willing to 'cross the aisle' or betray their own party. You may get a couple of backbenchers to vote for the other side sometimes but this is hardly ever enough to make a difference and is normally as much to do with internal party clique-politics rather than national politics. This makes it seem like a worse system than the US one as party discipline is even tighter and 'voting on personal conscience or interests of constituents' isn't even on the horizon for most politicians. But the parties themselves are more likely to compromise when necessary.
@Daryl, the only reason our system looks a little different at the moment is because we have a coalition government which occurs about once every 60 years and tends to destabalise the status quo.
