In an unprecedented frenzy of blogworthy activity, I’ve just created an Alfred workflow for quickly getting the range between two dates. After hours of contemplation, I decided to call it Date Span.
It uses PHP’s DateInterval to take a variety of datetime formats and output the range in various units. For example, give it a single date and it’ll calculate based on the current date and time:

Give it two dates (separated by to
) and it’ll calculate the difference between them:

And just because it’s friendly, it’ll remind you if the date is in the past:

I’m not thrilled with the icon I whipped up for it, and I’ve not tested my theoretical bash-centric guess at timezone detection. And PHP 5.3+ is required.
Enjoy, and please complain about anything that’s stupid!
Download DateSpan.alfredworkflow.zip or check it out on GitHub.