[jerhinesmith]

As a sometimes developer of web applications, relative dates nicely (for me) solve the problem of timezones. "10:42 PM - 15 Aug 12" means nothing without the relevant timezone information. "30 minutes ago" is timezone agnostic.

For non-commercial apps, lately I've been displaying relative time, but embedding the actual datetime (in UTC) as a title attribute.

[foxhop]

Agree. I prefer "ago" and your suggestion of a title/hover/hidden datetime is an even better idea!

recently I published a python module to calculate the ago: http://pypi.python.org/pypi/ago