[eluser]Phil Sturgeon[/eluser]
As BrianDHall has mentioned it is perfectly possible to create a UTF-8 compatible CMS that integrates with Twitter and other web services. I should know, I made one! :-p
The beauty of CodeIgniter is that if it is doing something you dont like, 9 times out of 10 you can just extend or override it. I haven't touched a thing in the core of CodeIgniter to create PyroCMS and have never even wanted to.
I've said it a few times. If you are trying to do something in CodeIgniter that your cant do easily, you are probably doing it wrong.