I feel that it's not the power cord thats the problem on mine, simply the whole it plugs into. I feel like it's loosened up after these 2 years of existence, and now its getting to be quite fidgety with how it the plug has to sit in it.
Not very handy for a handy laptop.
Also I'm just waiting for something to break on this out of warranty so I can get a new PB.
Apple care is a pain in the ass too, I've had to send my laptop in 3 times to finally get my creaky lid issue resolved, and once more to have them fix things that got broken during their repair - aka latch, and case wasn't sealed fully. On top of all this, it came back with a screw loose, they had jammed the laptop shut with this screw loose (one at the base of your LCD on the right) and it scratched the shit out of the little plastic rim on top right. Apple care has screwed me more than helped me it feels like. Except with iPods, they just replaced those whenever my HD dies...