Very pleased about this; I've been using RealStudio (now Xojo) for Mac and Windows stuff, and they're planning iOS support for later this year too, but I've been somewhat wary of spending $400 for the licence to build on iOS. I hope that B4I pricing will be broadly similar to B4A.
Incidentally, I do all my B4A work on a Mac - it works just fine in Parallels Desktop