RIM has confirmed to PCMag that it will be adding full Blackberry Enterprise Server support to its upcoming BBX platform in time for the first smartphone that will run it. The news should quell earlier concerns that it wouldn't be available on the first release of the smartphone, although it's worth noting that as of right now the PlayBook 2.0 beta that has been distributed to developers still does not have native support for RIM's enterprise infrastructure. BBX is likely to be an iteration on the PlayBook OS, which includes a smorgasbord of development options from native to Adobe Air to Qt to Android.
RIM says that the upcoming BBX phone will have the same screen resolution and aspect ratio as the PlayBook, 1024 x 600. This will ensure that apps written for the PlayBook will work on smartphones, but it also strongly implies that the phone will either lack a physical keyboard or will have one that slides out. RIM didn't rule out other screen resolutions in the future, but setting the first phone to that somewhat non-standard resolution is a smart move to maximize app compatibility in the short term.
Currently rumored to have the codename BlackBerry Colt, the first BBX smartphone isn't expected until early 2012. Little is known about the Colt at the moment, except that RIM needs to move quickly to release the phone before it becomes too marginalized in the US market. Full BES support will go a long ways towards shoring up its enterprise base, but whether that will be enough to compete with Apple and Android is an open question.