Mozilla is aiming for a more liberal submission process, although all apps will get checked out before hitting the marketplace. Sadly, they have also adopted Apple's Freedom from porn rule, so you'll still have to rely on Google to get that fix. If you're a developer, though, the “very quick screen process,” as a Mozilla official called it, should be pretty sweet.
At launch you'll have to use Firefox to access some of the more feature rich apps, but Mozilla is hoping that other browsers will adopt their runtime software and make Marketplace fully accessible on all platforms. Like other app stores, Mozilla will also take a cut out of most sales, but they're also open to developers choosing alternative payment systems; other funding will come from advertisements.
What's even more awesome is that you, too, can own your very own app store, building on top of Mozilla's source code. Mozilla's Joe Stagner explained that they're also “going to publish the source code for the marketplace, so if anybody wants to set up their own marketplace, they can do that, too.”
After the public beta period, Mozilla is planning to release Marketplace sometime later this year. If all goes well, it might actually be a good reason to give Firefox a second chance. In the meantime, the video below will give you an idea of what you've got to look forward to: