iOS supports convenient "Share" button,
that is available in pre-installed apps, such as Safari,
but can also be added to other iPhone and iPad Apps.
This may even work from PhoneGap
Windows 8 / RT apps support similar concept of "Share Contracts" between apps,
available on slide-in menu from right side of the screen (circle with 3 dots that look like arrows).
The idea is that each app should do one thing (very, very well),
and use services from other apps for everything else:
i.e. sending email, or sending note to Facebook or Twitter, or file to DropBox etc.
As usual, the "devil is in the details", so while this is not too hard to implement
(once you figure it out), it depends on platform, other installed apps, security etc...
Many years ago Microsoft implemented COM for very similar purpose,
and that is quite complex, but works quite well, so much so that WinRT is also based on COM...
What is needed is "platform independent" extensive structured communication
that is not complex and brittle as SOAP XML web services,
but is more "structured" than plain JSON REST HTTP,
managed by local OS when on local machine,
and by online service "broker" for messaging between devices...
"Smart" share for "Smart" devices :)