Pronunciation: 
In Dutch, the "G" in Guido is a hard G, pronounced roughly like the "ch" in 
Scottish "loch". (Listen to the sound clip below.) However, if you're American, 
you may also pronounce it as the Italian "Guido". I'm not too worried about the
associations with mob assassins that some people have :-) 

Spelling: 
My last name is two words, and I'd like keep it that way, the spelling on my 
credit card notwithstanding. Dutch spelling rules dictate that when used 
in combination with my first name, "van" is not capitalized: "Guido van 
Rossum". But when my lastname is used alone to refer to me, it is 
captialized, for example: "As usual, Van Rossum was right." 

Alphabetization: 
In America, I show up in the alphabet under "V". But in Europe, I show up 
under "R". And some of my friends put me under "G" in their address book... 