It certainly makes it easier, but there are still some management (or, more aptly, digital citizenship) techniques I employ.
To begin, we talk about appropriate use - what does it mean to use this device appropriately? I point out that appropriate use depends on the situation; using a phone with friends is more appropriate than using it when a teacher or fellow student is talking.
We also discuss why they might use it - I think we give students too much credit for knowing how to integrate these into the classroom.
It's usually a good conversation that takes about 20 minutes.
After that, I try and build in places for students to use devices - I'll say "take a picture of 2 right angled triangles" or "record a video of the lab". This models some good use of the devices. Throughout I ensure that the students are indeed using them for the correct task.
Inevitably, someone doesn't use it appropriately. If it's a first or second time, we'll have a chat - what they were doing, when they should have been doing that, etc. Nothing is set in stone - yes, you can text your mother if it's really important - I use my phone in staff meetings to send important messages as well. No, you can't play dots in class instead of working, you don't get that privilege yet.
After a couple warnings, they'll lose the device for the day - this is simply because I'm pretty confident they wont NEED these devices later. When everyone else is using them as well, I'll have to figure something else out!
In terms of laptops, my general rule of thumb is that if more than one student is interested in a screen, I should probably pop over and see what's up. It's general, and stereotypical, but 9 times out of 10 I have to redirect something.
Another good tip is to remember what they're supposed to be doing with a device. If everyone is supposed to be writing a paragraph to respond to a science journal prompt, the use of a mouse should be few and far between - anything more than a few clicks and we may have an issue.
Finally, we all need a mental health break. Depending on the student, I'll give them 5 minutes of Facebook time, or Dots, or whatever - I myself lose my head after about 3 report cards and need to take a brain break!
I'm pleased with the results - students are learning how to use the devices appropriately, which should hopefully carry over into other classrooms and their everyday lives.
Photo Credit: DanielZanetti (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0-2.5-2.0-1.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons