My OH is using my iPad for a conference abroad. He took it to check e-mail, read the web, and such. But we remembered that there's a lightning-to-VGA dongle (was available at the conference center) for a projector, so he actually ended up giving his presentations from the iPad. And then using apps like Sugarsync, he could access all of his recent papers and plots from his work computer that are auto-synced very quickly. And then also take notes with a nice stylus I got (there's an app by Evernote that allows written notes and syncs them through Evernote). Anyway, it could be done on other devices, but I still think it's awesome, given the stability and nice screen size / resolution of the iPad (4 in my case). I know my next mobile thing will be a Windows 8 tablet with an 11.8" screen or so, or maybe one of those foldable ultrabooks that can convert to tablets, but they are still really expensive at the moment, and the iPad's been great for small things. Very happy with it.
(P.S.: the only real need for a more portable "work" machine in my case is for travel... but I find that while traveling on conferences, not much work is done remotely anyway. To run a program or check on progress on a remote work / home machine, there are remote connection apps, even for iPad (such as teamviewer). Our household has not had a need for a laptop for a few years now--we sold off all of our laptops and netbooks).