Yeah, the controller ports on mine are beginning to yellow too. What I'm really wondering about, though, is the slightly different shades of gray between the top and bottom halves of the console (bottom being darker than the top) - what is this caused by? I'm also wondering if those who had their system yellow can confirm/deny that something like this was a 'symptom' of the eventual yellowing.
I'll post some pictures tomorrow if it'll help.