It's taken longer than expected, but Gamepark is on the brink of launching their Linux-based GP2X Wiz handheld gaming system—and they are planning to follow up with an open source app store this summer.
Gamepark is currently developing the SDK and plans to have the store up and running by August 2009. At that point, anyone interested in making games for the platorm can do so—although a pricing structure has not been announced. However, they do compare the experience to what Apple has done and they expect both free and paid apps to be part of their offerings.
Open source or not, I don't think the Wiz stands much of a chance (the name certainly doesn't help matters) given all of the stiff competition, but interested parties can pre-order the basic unit now for around $190 (without Wi-Fi—lame). [GP2X via TechRadar]