Research In Motion has made the client for BlackBerry App World, its version of the App Store, available to download today.

Users of BlackBerry handsets with trackballs or touchscreens, and running the v4.2 Device Software or above, can download the client from mobile.blackberry.com as of now, as long as they're in the US, UK or Canada.

We're having problems accessing it on our v4.5-running Curve, so it appears there may be some caveats to those system requirements. RIM warns that App World "may not be available on all networks" for example.

UPDATE: We were being told that our v4.5-running Curve didn't meet the system requirements earlier, but we just tried again, and this time we could download the client.

Of the 20 Featured Apps on the official website, one is a game - Gameloft's Brain Challenge 2: Stress Management. However, more are expected to be available on the App World itself today.

Games developers and publishers are excited about the new store, less because of the technical capabilities of BlackBerry devices - not a big leap from Java - but because of the popularity of the handsets, particularly in the US.