As long as we take the title seriously: "25 of the greatest..." and not "the 25 greatest..." I think the mouse-over text on the "Vorkosigan Saga" indicates that--the writer chose it not because it was important, but because it was fun.
Plus, I didn't read anything into the ordering of the books, except for maybe the names everyone knows, SF fan or not, first and all the rest next.
But, it wouldn't be my list 
There are nine books on it I haven't read, so I can't judge them. I would have chosen _Stranger in a Strange Land_ instead of _Starship Troopers_ for Heinlein. I love _Anathem_, but I would have replaced it with another future monasticism, _A Canticle for Liebowitz_. Besides, _Snow Crash_ is already there and is well representative of Stephenson's lovely mish-mash of oh-just-everything.
I'm currently revisiting the "Book of the New Sun". I read them when they first came out in the 80s and it's really nice to come at them from a point of view thirty years older, too.
2001 has a special place for me: going to the movie with a bunch of my friends for my thirteenth birthday (and afterwards having a cake with a big chocolate monolith on it!) and then consuming the book at the same time moved me into reading adult science fiction, a bad habit that continues to this very day I wouldn't have chosen the book, though, as a Clarke representation on the list I'd probably choose _Childhood's End_.
Having the fun-to-read factor considered was nice. I liked seeing Miles Vorkosigen there, along with the Hee-Chee.
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