Midcurrent has a nice article explaining a few ways to help untangle knots in your leader. Make sure to read the user comments too because there are some great ideas in there too.
One user asks about ideas for undoing knots in braided and furled leaders. I've never owned a braided, but I have been using furled for many years. I have found MONO furled leaders to be simple to untangle, but always thought that THREAD furled leaders are sometimes more difficult. Of course, some of this depends on the location of the knot. With both mono and thread, furled or not, the thicker section of the leader is easier to undo than the thinnest portion of it. A friend of mine recently said that with a thread furled leader of mine that I furled for him, he didn't have any issue untangling it.
If for nothing else, I like furled because they have virtually no memory (even after years of being rolled up) and I can furl them up at home when needed. I hope to be furling some up in the next few months to have for sale at Guys, Flies & Pies on February 12th 2011. If you are interested in buying one before then, let me know and I'll see about getting some before then.