I don't think there's any official "x pixels gets you a new camera" number.
When I bought my 7D, a few months later I noticed it had quite a few (10-15) dead pixels, so I took it back to the camera shop and got them to send it in for a warranty repair. I figured for that price, I deserve 0 dead pixels.
It can back still with 5 dead pixels, so i sent it back. Then it still came back with 2, so back again it went. The last time it came back, the AF wouldn't work, at all (I even tried some lenses in the shop), but thankfully a 'restore to factory default' in the shop fixed that.
This whole process took 11 weeks all up (I was living in The Netherlands at the time btw, the repair centre was somewhere down south near the Belgian border), and i went on a trip to luxembourg with only a crappy p&s.
Also, I did try the '30-second cleaning = pixel remapping', but it didn't work. Maybe it's my camera, firmware, all 7Ds, or if they were just particularly stubborn pixels, I don't know.