Anyway, the details...
The E5cs main difference is that it has a cross-over circuit and fits 2 drivers in each earphone so you get an amazing dynamic range. The bass reverberates through you head like you're in a disco or something. The E2cs were great on the high ends, but these E5cs do the whole range amazingly well.
The cord is shorter and lighter, not exactly sure why. You can use the triple-flange sleeves which seem to go deeper into your head. They feel a bit weird, but I think I'm going to like them better than the normal flex sleeves.
The only thing is that they're $500 vs. $100 for the E2cs. Are they 5X better than the E2cs? Well, think of the power law and wine. It costs more and more as you get closer and closer to the peak. It's a matter of your priorities I guess. I don't think that they will be worth $500 to some people, but I'm happy. You could get a round trip ticket between SF and Tokyo for $600 or you could go and buy a few expensive Japanese musk melons. it all depends on what makes you happy I guess. ;-)
You can buy them on Shure's site. And, no, they don't pay me to do this. ;-p
UPDATE: Matt from Shure has started a blog. Check it out!
UPDATE: I've started a new gadget blog called Joi Ito's Stuff