Yes! They are usually published in The Wiscon Chronicles, available from Aqueduct Press.

http://www.aqueductpress.com/current-pubs.php

(Scroll down or search for "Celebrating Wiscon".

Each year is edited by a different person, and there are no guarantees about what this year's will contain or whether it will exist, but looking at the contents page of the last few says Guest of Honor speeches are very likely to be included.