The TF2 team at Valve posted a curious message on their blog today. I think they are teasing us in the funniest way about the next update, which could more than probably be the engineer's: a Cannon-appended canine unit? Wait Wait Wait... So there will be "pets" in TF2??

EDIT: In fact I've been horribly fooled. This is not teasing for an incoming update, this is Valve's way to acknolewdge the quality and the humor of this fake update giving access to a 10th class. This is great work, the website looks like an official one and the class is described with its strengths and weaknesses, the achievements you can unlock, etc. Good prank!