I actually think they did.
Currently the domain name is protect by a WHOIS privacy protection but still i think the domain BlizzardAllStars.com is registered by Blizzard.
Now one could argue that this evidence is pretty thin and it is. But i just got a gutt feeling that Blizzard is behind this. Blizzard uses a variety of Domain Registrars but they often use Godaddy.
Blizzard All Stars also reffers to DOTA 
So that is another hint that Blizz regged the domain name.
The popularity of Defense of the Ancients has increased over time. The scenario was featured by Computer Gaming World in a review of new maps and mods in Warcraft III. DotA Allstars became an important tournament scenario, starting with its prominence at the debut of Blizzard’s BlizzCon convention in 2005. DotA Allstars was also featured in the Malaysia and Singapore World Cyber Games starting in 2005.
I guess we will find out what Blizz is gonna do with this domain name Currently the domain name is not resolving.
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3 Responses in other blogs/articles
[...] Story can be read here. [...]
[...] more here: Did Blizzard Entertainment register the domain name … [...]
[...] wich is related to their DOTA game. That post was original posted here. Back then the domain name was not resolving so there was some speculation if Blizzard was behind [...]