Here are some things I noticed while reading the civ4 manual at work:

1. there are now worker boats to improve the ocean squares!
2. settlers move 2 squares now
3. you can now move on the same square as an enemy and not attack them!!!
4. mounted unites can’t fortify
5. you can fortify til healed
6. other civs can’t go in your territory until they have open borders treaty with you
7. you can have mult religions present in a civ
8. cottages give you commerce on a square now – not roads
9. frams are like irrigation
10. also camps, pastures, plantations, watermills, quarries, etc
11. You can have a jewish temple, christian temple, etc

Sorry if that was a bit incoherant, but I’m in a hurry to play!