Well, don't let the silence fool you: according to BGR, the sixth version of BlackBerry OS is in the making and first images start to leak.
BGR made some good points about the new UI:
"Something big for OS 6.0 is the homescreen. While we didn’t see any sort of widget support, it appears RIM has made the homescreen completely customizable with pages. You can have your applications on the main page, then slide left or right to another page with different applications and browse that way. In the homescreen screenshot above, you’ll see a sliding field towards the bottom, and you can slide that up, and reveal the first page of applications, and you can then slide that to show the different groups which correspond to the different homescreen page. Favorites, all, home, etc.
Another big thing for OS 6.0 is modal popups with gestures. If you tap and hold (obviously a touchscreen device is required), you’ll get a 9 icon group centered on the screen which is basically a pretty context menu. For instance, you could be composing an email, and instead of pressing Menu + Send, you could tap and hold on the email, see the popup window, and hit the send icon there. Another use would be when emailing photos or videos from your device, just tap and hold on an item there, see the popup, and then just send the item. That way you don’t have to deal with going through the normal menu options which has gotten convoluted with all the various social services/networks available."
You can read more about it in here.