If you're working unpaid overtime in the hopes of one day making partner at your company, you've already fallen for a scam. It might not be an intentional scam, but it works out that way. First, you have to figure that the smaller the company and the younger it is, the more likely it is that it won't even exist any more by the time you are supposed to make partner. Second, if you do happen to work at a place that is likely to exist later, just take a second and count the number of your coworkers who are doing the same thing as you. Now ask yourself whether all of you are going to get a turn at being partner. How many partners are there now, vs how many employees? And how many employees came and went at the company for each of the current partners? Your odds are not good. Third, given that your odds are not good, you might do better, cash-wise, working those extra hours at a second, part-time job.
Mokalus of Borg
PS - At least that way you get paid.
PPS - For the few who do make partner, though, their time will be worth it in the end.