Kathy Sierra over at "Creating Passionate Users" put up a post the other day called "Dignity is deadly." - Paul Graham. The discussion that followed in the comments focused mostly on the relationship between of innovation and professionalism. The question being debated is whether as companies grow, and typically become more "professional", do they lose their creativity?
I guess I weigh in on the side that being "professional" or "passionate/creative/innovative" is not inherently an either-or proposition. I believe that the important factor is authenticity. If "becoming professional" (however you wish to define it) is not your true nature, then it is the wrong approach. It is essential that you are true to yourself and true to your customers. If that means t-shirt and jeans, so be it.
Being authentic means never wondering whether or not you sold out.
[update: significant typo discovered! inserted "not"; underlined above. My apologies to anyone that read this and wondered what the H___ I was talking about]