Here is the link for the GW2 BETA Client to use for this weekend
This is also located in the official BETA forums (currently down due to server implosion =D) so use the link above to download!
Don't forget to tell us if your playing this weekend in THIS THREAD
so we can ramble across Tyria together =D
EDIT : Replaced link with one from the BETA forums. Anyone who downloaded the previous link do not worry, it is exactly the same. Arena-net just chose to also update the old client to save people who retained it from downloading it all over again. Your download should be around the 13GB mark.