According to Engadget:

It’s day three of RIM’s BlackBerry service outage in much of the world, including Europe, the Middle East, Africa, India, Brazil and Chile. But now the problem appears to have spread into Canada — RIM’s home turf — and we’re even hearing reports of some service issues in the US as well. We’ve reached out to RIM for comment, but we’d like to hear from you. Let us know whether or not you’re having issues in the poll below, and jump past the break to sound off in the comments.

Update: RIM has posted the following statement to its BlackBerry Service Update page:
BlackBerry subscribers in the Americas may be experiencing intermittent service delays this morning. We are working to resolve the situation as quickly as possible and we apologize to our customers for any inconvenience. We will provide a further update as soon as more information is available.

Update 2: RIM UK has also posted a statement:
We know that many of you are still experiencing service problems. The resolution of this service issue is our Number One priority right now and we are working night and day to restore all BlackBerry services to normal levels.