That story you link to is not proof. If you look closely, that sticker you mention is on the RAM the author is ADDING to the MacBook Pro, not on the existing RAM module. (Notice the existing RAM module is blue, and the 3rd party one is green, and the green one is the one with the sticker)

I have a new MacBook Pro (the SD card one) and it has instructions in the manual IT CAME WITH on how to replace the RAM and hard drive. Apple wouldn't give you explicit instructions to void the warranty. Replacing RAM or hard drive does NOT void the warranty.