"I somehow really doubt that Silk will translate in a faster user experience. Of course, marketing does wonders."

As I understand it (that is what you call a disclaimer), Silk will operate in a fashion similar to Opera Mobile. Requests are routed to a proxy farm which transcodes and optimizes content for a known target browser. In Amazon's case, they have exceptional knowledge and control over that platform.

It's probably the one thing other than massive superior content that Apple might envy. :-)