I work almost exclusively at coffee shops, but not that I like coffee or anything.
When I take a break in an office, I spent a few minutes reading slashdot and feel slightly refreshed.
But in the coffe shop, I spend a few minutes talking to some hot girl studying. And then I feel really refresehed.
And I work more. I'm much more willing to think "Yeah, lets go back to the coffee shop for anouther couple hours" as oppose to "lets go work in our slightly dark offices again"
In fact, I'm pretty sure if I ever own my own company, I'll just give the employees starbucks cards, cell phones, and laptops. Screw this whole office or cubical bullshit.
Ben