Unfortunately, it's not completely up to BlackBerry in this case. Company man, Alex Kinsella, recently tweeted the above snippet about BBM for iOS in which he states it has been waiting for approval for the last two weeks.
According to CNET's Jessica Dolcourt, Apple takes around 4 days to approve an app, which shows BBM has definitely been delayed from launching on iOS because of Apple, not BlackBerry.
What about BBM for Android then? Well, no comments have been made about the submitting the app to Google Play, but since Android is a pretty open environment, we're sure that Google has given BlackBerry the green light already. It's possible that they are, instead, waiting to get Apple's approval to launch both BBM for iOS, and for Android at the same exact time.
Hopefully BlackBerry gets through Apple's gauntlet soon, and you guys out there with iPhones can finally enjoy #BBM4All.