Yeah, Jaiku is way ahead in just about every department.
But, because Twitter was the first mover in this space, they got the lion's share in terms of users. And once people get their network built up, switching to something else becomes a pain....even if it's better!
All Twitter has to do at this point is implement the features that Jaiku and Pownce have created...I'm actually kinda surprised that they haven't done so yet.