I'm 99%+ certain that WebOS is a Linux platform, so
it is open source by definition. You can read the GNU licensing stuff to further understand, but essentially, you can't close or stop development if you use a Linux (or other GNU license) base. But there ARE many things you can do to make money on support (Red Hat, et al) and have "some" level of control.
I believe the control is through the the stores, in what they do and don't publish/certify, and probably the associated ability to use the WebOS name, which I'm sure it trademarked. So, one could write an app that doesn't get accepted in the store, but you'd have to make it available some other way that obviously would have way less visibility (today at least) and you'd probably have to be real careful in how you state it's use or use WebOS in the name or description. EG, (I'm no lawyer so this is my layman's understanding) I bet you could say it runs on WebOS, and properly state that WebOS is trademarked and owned by Palm, but you might get some grief if you advertised it as a "WebOS app", or a Palm app, which might be an infringement on the use of a trademark.
I'm not a coder and don't follow this too closely, but I'd bet the difference in the quality or polish of the apps are largely based on the development kits offered, which is also another part of the control that can be exerted on how apps get developed, the look, feel, consistency, etc.
So for example, Palm has you develop WebOS apps with their dev kit that doesn't allow talking directly to the hardware (like the graphics processor or radio). But if you have unix/linux root authority, you can get to ANYTHING in a Linux system, (unless they put in some firmware interpreter of the root shell that I bet would violate the Linux GNU license). But depending on how they did the drivers, which could be in firmware, or even if you write to them - before they add that capability to the dev kit - you would likely not get that app published on their store, and they could in fact tell you that you voided the support part of your warranty as a user if you installed said app, etc.
Having said all that, WebOS appears to be VERY open, evidenced by Homebrew and Preware as mentioned by others, the latter being an example of something I expect Palm could say "you can't use the term "Preware" it's a violation of our trademark, but they've not done so.
Hope this helps.
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