FYI, I just saw this pop up on CNN:
BlackBerry outage spreads to North America
My access problem started a few days ago, which corresponds with when these Blackberry outages started in EMEA region. Are your servers located overseas, or fed through subnets with overseas IP addresses? If so, this might be the reason for the problem.
It might be best for you guys to wait a couple days and see if this goes away when RIM gets their act together.