Most obviously, the Basic Rules card has a new layout. Now it's got little half-size icons of two cards, one saying "Draw 1" and the other saying "Play 1". When playing a new Draw or Play rule, you can cover the appropriate icon and make everything look proper.
A few cards were reworded to be clearer. For example, the Poor Bonus card had an added line about "In case of ties, nobody gets the bonus." Interestingly, they kept the X=X+1 card but renamed it Inflation. Also, they got rid of Go Fish and I Need A Goal (good, I never really liked either of those cards) and replaced them with Jackpot!, an Action card that allows you to draw three extra cards.
I also took the opportunity to edit a couple of my custom cards. I reworded Fast-Track Legislation to be simpler to play, and I corrected the spelling of Småkakar to Småkakor. I also got rid of Hey, That's My Stuff because nobody else ever understood it and it never actually turned out to be any fun anyway. Oh, and I did something sneaky: I stole Play All from the 3.0 deck and added it to my custom deck, which now has two Play Alls. I love that card. :}
I need to update my Fluxx custom card page. Maybe tomorrow.
Ooo and I got some other games as well: Eco-Fluxx, Set, and Munchkin.