But check out: http://www.slidedeck.com/pricing-b/
These guys give away a "GPL Branded" branded version of their code and then sell two premium "unbranded" versions that allow licensing of servers. They have some impressive clients.
I'm just about done with a project of my own that is similar. I was just going to open source it and then use that source to create a demo to go and find financing for a bigger server side project (with a more clear cut monetization strategy), but seeing this made me take pause.
I'm thinking - could I monetize the client source in the short run and raise less money? This seems like an option - but it also raises lots of questions:
1) If slidedeck's code is "GPL Branded" - how do they enforce that it's branded? Couldn't I just remove the branding, release my update to the community? (That would be a crappy thing to do, but would it be illegal or against GPL?)
2) While it's quiet obviously - the right thing to do - Outside of premium support models what are the main drivers for companies to license this code outside of the honor system?
3) Given Slidedeck is GPL what protections do they have from flat out plaugerism and people coying their code and selling it for less? Are there legal measures that can be taken to prevent this? How could they enforce this? Copyright perhaps?