The moral of the story is that Steam Guard should be (and/or should have been) enabled on all accounts by default...
Steam Guard prevents account sharing which happens alot and is the reason people do not do it. Personally I use it but do understand why its disabled on some accounts.
Hijacked? As far as I know all they managed to do was annoy people by triggering automatic password resets, no accounts were actually compromised.
Going on what I read and watched it was more than just triggering automatic password reset, seeing as it's apparently fixed now I guess it's OK to post the following YouTube video.