Without support for mobile devices, the beloved PersonalBrain will quickly lose its usability in today's multi-device, cloud-based world.
As for me, I've had to make the hard decision to start looking for an alternative application. I haven't switched yet, but if I find an adequate app for my i-Devices, I'll make the switch reluctantly.
A side comment...
One thing that PB suffers from as much as Google and a number of other organizations is the failure to respond to its users in its forums. Maybe I'm wrong, but I don't see any PB staff answering the burning question of whether there's any intention to take PB mobile. The WebBrain is clearly not the answer... featureless, and just a viewer.
So long, Brain. Maybe if I hear you've gone mobile I'll come back and take another look.