Something which a lot of people don't realise is that (a) it is possible to write free/open software for closed platforms and that (b) it can be fraught with interesting licence issues. Many of you will, by now (hopefully), be aware of the implications of copyleft licences such as the GNU GPL. Some of you may even be aware of the creative commons and their range of licences which include clauses such as non-commercial use.
When you're looking to include free/open software or other artefacts into your closed platform you need to be very careful to audit their licences to ensure that you're not doing something you're not licensed to do. For example you cannot even aggregate GPL content into your product without complying with certain terms around advertising the fact that it's there, offering to provide the source including your changes, etc. It can get very dangerous if you're incorporating source code files directly into a product binary. There are compatible options such as the BSD or ISC licences though they provide less strong assurances of freedom.
If you do decide to go down the path of using free/open software and resources on your closed platform (and these days, the proliferation of Linux-based products suggests that you are far more likely to do so than not) then you should ensure that you're aware of the licences present on your system and the implications of having them there on the delivered product.