Oh, boy! Definitely lens envy here!
Would love to have the reach of a
500, and a
600. Well,
that. Would. Be.
Awesome! 
I've heard about the Tamron 600--there were a lot of people waiting impatiently for the shipments to catch up to the orders.
As an afterthought, I picked up an extra battery when I bought my camera. Best move I ever made.
That way I always have a fresh battery available. Now if I just had a freshly charged memory at all times so I'd remember to bring that extra battery!
