I have heard several times that the Sarbanes–Oxley Act had a profound affect upon how business is performed in the US, but no one has ever explained to me what all the fuss is about. Can you? How, in particular, does it affect a start-up company?
It depends on the types of services you offer and who uses those services. As a start-up it's easy to think this is N/A for you but if any of your clients are publicly traded or use your products/services as part of their work for their clients who are publicly traded you may find that this impacts you as they will be asking for things like audit-trail capabilities, etc.
Senior management of publicly-reporting companies has to certify that the financial statements are correct now, due to Sarbanes-Oxley. This requires massive audit expenses (to be sure that the financial reports are right), and there is significant liability for those executives if the financial reports are wrong. So a public company can either spend a ton of money on audits or not be public. It's a lose-lose situation.