Following reports scattered across the internet and the tips that have been pouring into my e-mail inbox this afternoon, it appears that BlackBerry Internet Service (BIS) is down for users in many parts of North America. Beyond that, there doesn't seem to be a specific carrier, region, or ETA to a fix.
Though this isn't intended to be a comprehensive list, here are some of the problem areas reported throughout the day (to be updated as users report issues):
How's your BIS working? Let us know in the comments section below!