This has apparently become a trend. Releasing a talent calculator weeks before release(Months even) to give eager players a chance to plan their progression. Diablo 3 did it, even Guild Wars 2, now Borderlands 2 also gives you that option.
Borderlands skill tree's are pretty straight forward even on the second game, but just so you wont regret putting extra point on a skill, or spend time in-game deciding what to do, you can plan out how you want to build your character right now at their official website. Head over to the characters section, and you can start your theory crafting on character building.
It's just a week away. Soon, Phycho Midget parts will fly, groups will be formed, and tons of weapons will be looted. Borderlands 2 hits stores September 18 on Playstation 3, Xbox 360, and PC.