There is also a similar story for Siebel (Northwestern Mutual I think?). In enterprise software, buying from small companies is not the norm, so if some large organizations invest in your product, it can trigger the larger market to believe in you. I believe the trick is to make sure the "big" accounts you take on aren't ones that are going to take you too far off your normally planned roadmap. If you find yourself building one-off features, one for each customer, you are in for a world of hurt. If your big customers drive you to build your roadmap faster or more aggressively, that isn't always a bad thing.