Indeed, the MagSafe connector is quite well designed. I'm not sure how rugged it is, I think it's purely intended for home/office use. Rather than making the cable well protected (like my current laptop) they've opted for using a small magnet to hold it in place and design the cable to withstand being yanked out.
So I rather suspect the IP rating of that particular connector to be rubbish. Perfectly fine for Apple's use case, but I can see Panasonic and others saying, "thanks but no thanks".
At the very least though, it would be nice if all laptops could have a standard charging voltage and current, so that suitable adaptors can be made.
Right now, I've got a few laptops: Lemote netbook that runs 20V 2A with a plug that's compatible with newer Toshiba laptops, a few older Toshiba laptops that run 15V (one 3A the other 5A), an Apple MacBook that runs anywhere between 16-18V with constant current, and a Panasonic CF-53 with its 15.6V supply.
Most are constant voltage: the Apple being the notable exception. I suspect in Apple's case, the power supply charges the lithium pack directly and the machine permanently runs from the battery. Take the battery out, and the machine won't run, at all.
If they agree on the electrical characteristics, that gets us most of the way there. With the myriad of form factors, from netbooks, ultrabooks, tablets and desktop replacements, it might be difficult to get consensus with a connector format. I can see there maybe being 2 or 3 variants of a standard, but at least with a common electrical spec, it takes a good amount of guesswork out.