I think that the story here is that it's cheap and built into a watch, although I'd have thought that a handheld device would still be better for aiming as well as battery life.
For example, pretending to not discriminate on age by asking precisely selected interview questions.
"Reaction time is a factor in this, so please pay attention. Now, imagine you see some children on your lawn. What's your reaction?"
It depends on how the app works.
Does it work like an old-style program that performs some computation and does something, or is it a 'cloud'-based app, i.e. it sends all the raw data off to some server somewhere?
Given that it is said to send an email instead of just display a notification, I suspect the latter, in which case you're sending those potentially 'followers only' tweets off to a third party.
I could totally see it being coupled with email accounts
Yes, if either via a separate program or as part of an existing service, everyone had a personal mailing list, the 'social network' aspects would be separated from the transportation method. You would 'follow' someone by sending them a subscribe message (or your app would do it when you clicked a button).
A reader could display a digest of all such mails from the people you follow (maybe sorted by tags added to headers).
Someone without any specialized program could still subscribe and get your mails. Conversely a webmail service like GMail could dress it up to look G+, where someone replying to one of your messages would appear as 'posting on your page'.
The initial draw of a social network is the ease of broadcasting your (possibly inane) thoughts to everyone who wants to hear from you. You don't do that to everyone in your contact list because they've not signed up to know what you had for breakfast. A way of collecting a willing audience is all that's needed.
And all the others were uploading an online copy too, so this isn't a like-for-like comparison (I think that DropBox, at least, supports direct local network copying but would probably be making the online backup at the same time).
It wasn't threading, it was displaying a thread as one scrollable page that was the innovation. I'd not seen a newsreader or mail client that did that before. Combined with collapsing of quoted text (which was an old idea, I think it was in Eudora or Xnews or something, at least), it's an easier way to read through a thread, removing one level of navigation (paging through messages merged with scrolling down a single message).
You should consider creating par2 parity files, which can repair as well as detect corrupt files.
All day long, web pages you visit will be filled with pleasing images.
Also there was the PalmOS Fossil watch (a stylus, but no keyboard).