Commonly when I look around the Internet, I find that people are generally using CSS hacks to make their website look the same in all browsers. Personally, I have found this to be quite time consuming to find all of these hacks and test them; each change you make you have to test in 4+ browsers to make sure it didn't break anything else.
About a year ago, I looked around the Internet for what other major sites are using (Yahoo, Google, BBC, etc) and found that most of them are doing some form of browser detection (JS, HTML if statements, server based). I have started doing this as well. On almost all of the sites I have worked on recently, I use jQuery, so I use the built in browser detection.
Is there a reason you use or don't use either of these?
The problem is that you only really get one shot at the css (since it is pretty much static content at the client)... you can't (easily) adapt it to suit on the fly at the client - so for those tricky incompatible cases (and there's too many of them), detection is sadly the best route. I can't see this changing very soon.
With javascript, you can often avoid much of this pain through libraries like (as you state) jQuery - and checking for functionality support rather than identifying the specific browser (most of the time). There are some cases you need to know exactly (the box model, for example).