Details about Research In Motion's forthcoming application storefront have emerged with some surprises. Among them, the requirement that users and developers alike have PayPal accounts for the sale and purchase of applications. What also may be distressing is that legacy BlackBerrys will be left out in the cold.Excitement among the BlackBerry faithful is mounting with the approach of its application store. Oddly dubbed "BlackBerry App World" (did they get the name from George Lucas?), the store will be a place for BlackBerry users to find and download applications for their devices. Yesterday, App World went live for developers, giving us a peek at how it will all work.

One of the first things that caught my eye was that in order to purchase applications from BlackBerry App World, a PayPal account is required. PayPal is used by auction sites such as eBay to facilitate payments between private parties. It appears as if that's how App World will work, in a sense. It will serve as the hub for developers and buyers to meet. RIM doesn't provide too many details about how payment will work, but we have to assume that RIM is going to take at least a small piece of the sale price, as will PayPal, before developers get their cut.

This makes sense in that it negates the need for developers to forge relationships with the myriad wireless network operators. App writers can then avoid the tangled mess that is the network operators' third-party billing systems. PayPal looks like it will be a huge (if not the hugest) beneficiary of App World.

Beyond PayPal, it looks as if RIM is giving a not-so-subtle message to users that they need to upgrade their devices. The minimum system requirements include BlackBerry OS 4.2.0. Many of RIM's BlackBerrys can update to at least that OS, if not a more recent one. What the older models can't do, however, is re-configure their hardware.

Legacy BlackBerrys, such as the ever-popular 7290, will not be able to use App World. Why not? BlackBerrys with trackwheels aren't supported. According to RIM, your BlackBery has to have a trackball or SurePress to work with App World. The complete list of supported devices includes: Bold 9000, Storm, Pearl Flip Series, Curve 8300 Series, Curve 8900, 8800 Series, and the venerable Pearl Series. If you're rocking an older 'Berry, you're out of luck.

The last bit of big news to come out of Waterloo is the pricing structure for App World. Developers will be able to offer free applications, but the minimum price for paid applications is $2.99. This is in stark contrast to the iPhone Apps Store, which lets developers charge as little as 99 cents for their apps. In fact, 99 cents is by far the most common price for paid applications in the iPhone Apps Store.

RIM didn't explain why it set $2.99 as the minimum price, but I bet it has something to do with its partnership with PayPal. The question this raises is, how will developers approach pricing their apps? They won't get any direct revenue if they offer it for free (unless they work in some sort of advertising), but the $2.99 price point may put off enough potential buyers that developers won't sell as many apps as they'd like.

For the moment, all we can do is sit back and wait for everything to shake out.

If you're interested in learning more, you can sign up here to receive updates from RIM.