Joe : I already proposed a “desktop-entry-hotplug-spec”  some time ago. I sent it two times and didn’t receive any feedback, so I wasn’t sure whether it is considered important.
The other feature you demanded (actions for files) is IIRC already implemented by KDE. I’m not sure how we should tackle this and I am not so happy with the KDE system.
[Desktop Action reSize640x480]
Name=Scale to 640x480
Exec=mogrify -resize 640x480! %U
While it allows for maximum flexibility we’ll end up with a can of worms when internationalizing this since it will be distributed with each application, especially with routine actions like printing. Also, it doesn’t consider how many items are selected – it is common to use ngettext() for internationalizing strings referring to countable objects.
It would really be great if we at least had some actions – maybe similar to those in  – for printing and enqueueing. Applications would simply provide a special Exec parameter, and we could immediately see that an application provides this capability.
Oh, and while we’re at it I also have an old “keyword-spec” draft that might be of general interest. I’ll sent it to you by email to get some feedback.