The exact title of the patent is "Temporary keyboard having some individual keys that provide varying levels of capacitive coupling to a touch-sensitive display." In the patent, BlackBerry notes that such overlays are already commercially available, but only to type on. The QWERTY that BlackBerry has patented also doubles as a touchscreen input.
The images of the physical keyboard in the patent resemble the odd QWERTY keyboard seen on a prototype of a high-end device codenamed the BlackBerry Windermere. That keyboard lacked number and punctuation keys. This could mean that depressing the keys will input letters, while using the touchscreen input of the QWERTY will input numbers and punctuation.
BlackBerry has tried other ideas in an attempt to improve the typing capabilities on its smartphones. Back in 2008, it debuted the SurePress clickable QWERTY on the BlackBerry Storm 9530. The idea was to make clicking on the phone's glass feel as though the user was pressing a physical button. The idea flopped even though it was improved on the BlackBerry Storm 2, and was never used again by the manufacturer.
"A physical keyboard having a plurality of individual keys temporarily overlays a touch-sensitive display. Each individual key selectively provides either of a first level of capacitive coupling and a second, different level of capacitive coupling to the touch-sensitive display. By one approach the key provides that first level of capacitive coupling to the touch-sensitive display when a user asserts the key (for example, by pressing upon the key) to thereby communicate to the touch-sensitive display a selection of that individual key. The key can provide that second level of capacitive coupling when a user touches, but does not assert, the individual key. So configured, this second level of capacitive coupling serves to communicate to the touch-sensitive display an input instruction other than a selection of that individual key."-BlackBerry patent filing
The patent was filed in August 2012 and while some of you might think that this would prove BlackBerry's case against Typo, that suit is about the actual design and look of the keys, which resemble those on the BlackBerry Q10.
BlackBerry patents temporary QWERTY overlay
source: USPTO, BlackBerryVietnam (translated), BBNews.pl (translated) via BerryReview