Can a developer with an app in the market also distribute to un-registered (rooted) devices? I'm looking to root a tablet device, to limit access to certain settings, and to remove the ability to get to the Market (long story).

However, I do want to get some apps that are available on the Android Market onto the device.  Is there any restrictions to app developers selling their apps in the market to also distribute their applications outside of the market.

Links to good references get bonus points.

Thanks!
I don't think there's anywhere to cite where Google has said that putting your app on the market is not exclusive, but I'm sure it's allowed, since there are a lot of different alternatives to the Market and you can even download versions of apps available on the market through other means. In certain cases, like Tasker, getting it directly (not through the market) is even encouraged by the author.