Open source has become standard in silicon valley, with nearly every software startup planning to release at least some code. So far, they've found five main business models:

1. Sell support services. This is the traditional Linux model, prototyped by Red Hat. It's still a part of most open-source business plans, but on its own it's rarely enough for startups trying to grow. The problem (for the startups) is that anyone can redistribute the code and sell support or consultancy services, so there's nothing to stop an Oracle (NSDQ: ORCL), an IBM (NYSE: IBM) or a Novell (NSDQ: NOVL) from grabbing most of the services revenue.

2. Build (or run) hardware.

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