I would certainly agree that a blackberry/similar device can be a useful tool for an SM. I would say though, that saying a device like this is needed for an SM is going a bit too far.
I agree. My husband's got a blackberry for his job, and watching the change between before he had his corporate leash and afterwards, I don't know that I'd want that kind of connectivity. His company purchased it for him, and since he has it he's expected to be on-call 24/7, answering emails at 3AM if they come just because that's when his boss felt like working.
IMO, if something's happening that's that urgent, and I'm not there, and it requires my attention that badly, call my cell phone. During the times of the day when I'm not present for things and it would be appropriate to email, I check my email about 30 times a day anyway... having your email on 24/7 just invites situations that make it so that you can't ever leave work... which makes for mental breakdowns, which is definitely not what an SM needs!
In a lot of ways, what we do, and as a result, what we would use (or do use) our PDAs for is very different than being obligated to wake up and answer an email at 3am from your boss.
I work as a freelance SM in NYC, which means that I am oftentimes in crappy rehearsal spaces that differ from day to day. I don't have an office to run to during a break to shoot a quick email to someone if I need to. For me, having constant access to my email has proven to be a necessity, but not one that has become an obsession. I don't need a 'Blackberry Blackout' or find it hard to put my phone away. It has been amazingly helpful to have it on hand though. I can read and write emails on the bus, or on the train. It is a real time saver in that sense to be connected.
Most importantly though, I can also choose not to answer an email (the same way I choose not to answer a phone call) if I don't feel it's a top priority to stop what I'm doing for it.
Nobody owns me and learning when to say no, no matter how often you're connected is just as important as anything else! Especially for us SMs. Technology related or not, I'm learning as I get older to learn that it isn't the end of the world to say no.
Also, sort of along this same vein, I've noticed that since I've been in NY, many of my actors and designers will now text instead of call to relay information, and I love this! It's so much easier to get a text that says "Trains running slow, I'm 3 blocks away" then have to run out of rehearsal to pick up the phone. Even my directors will text! It's really great.