As a Lightning user I often wish that all events would arrive at my Inbox as invitations in the iCalendar format. This way I could just click the accept button and it would be added to my calendar. But they don't. Often people just write you a text-based email when they want to invite you somewhere. So you right-click the email, choose convert to event and a new event dialog opens with start date set to next full hour. Not quite correct unless you're really lucky.
This is why I'm working on an extension to Lightning which would fill in dates and times automatically from email content. The basic idea is that localizers can define most common ways dates and times are referred to in their language similarly to how they localize Lightning itself. Using these patterns event dialog can be much smarter about setting start and end times and in most cases you wouldn't need to correct them at all.
Since Lightning is localized into 38 languages and language variants I need your help. If you fluently speak a language other than English and would be willing to spend some time to localize the patterns and test this prototype on your emails then please leave a comment below. Be sure to include your email and language of choice so I can send you a customized pattern file and prototype. Do so even if you speak only English as you can still help with testing. Feedback on when it guesses correctly and when not is crucial to improving the extension. What works great in English may not work well in your language and of course everyone's email is different too. With your feedback I can improve my extension so that this functionality can be included into Lightning later on (the curious can follow bug 403222 where more technical information will be posted).
Merike Sell, Mozilla Calendar Team