There's a school of thought which greatly admires "bi-partisan" approaches to solving political problems. The idea of representatives and senators putting aside their differences to "reach across the aisle" and work together seems admirably, if only because our social training all points towards the importance of compromise in order to get along with others.
However, I'd like to question whether there are often pieces of legislation which are genuinely bi-partisan.
Some legislation is essentially non-partisan. Instituting a national alert system to help track down kidnapped children, for instance, is hardly something which has a major political faction aligned against it.
In other cases, there's legislation which applies to factions within each party -- a result of the fact that our two major political parties include sub-factions which disagree with each other on major issues. For instance, "bi-partisan" immigration reform might draw support both from the business faction within the GOP and the pro-immigration faction within the Democratic Party, while being opposed by labor focused Democrats and immigration focused Republicans.
Often, though, a supposedly bi-partisan bill is actually a bill which is very much of one political philosophy or the other, but which is for some reason able to draw enough support from the most "moderate" members of the other party, sometimes by watering down its provisions.
For instance, on the current health care legislation, the bill itself is pretty clearly a bill coming from a Democratic Party mindset. It rests on the four pillars of guaranteed issue, individual insurance mandate, community rating and subsidies for those who can't afford their own coverage. Once the idea of a "public option" (which had been a sop of sorts to those on the left who would much rather have seen a single payer plan) was dropped, there's really not much else that can be done within the context of the bill's structure to make it less expensive or more amenable to a conservative approach. The changes which have been made in the name of bi-partisanship (reducing fines for ignoring the mandate and not having insurance, etc.) don't really make the structure any more attractive to conservatives, but do make it less likely to work if liberals are actually correct that such a system could work. (Rather than being a dud as it's been in Massachusetts.)
Similarly, in the fight over the stimulus package -- the "bi-partisan" solution offered to bridge between those who thought there should be a massive spending-based stimulus and those who didn't was, "How about if we make it a little less massive." But really, if your two positions are, "We need to have a massive spending-based stimulus" and "We don't need any stimulus, and the debt will hurt the country" saying "We'll spend 700B instead of 1T" isn't really a compromise between those two positions.
To the extent that the two parties really do represent different political philosophies, bi-partisan solutions are in fact pretty rare. And that's not necessarily a bad thing, since if two governing philosophies suggest two different solutions based on differing ideas of what works -- something situated halfway in between (or a half-gutted implementation of one party's idea) is less likely to be satisfactory than either extreme.