Apparently, any extra space on your lock screen is wasted space, according to the Android L design mantra. But displaying all recent, relevant information does make sense, and Google appears to be prioritizing phone calls, then messages, then calendar events.
Tapping a particular card expands it, allowing you to drill down into email messages, for example. And swiping it away erases it, as is now expected.
Apple’s iOS 8 has a leg up on one productivity feature, however: the ability to set “VIP notifications,” where you can ensure you know the instant an eagerly-expected email arrives. Otherwise, Android L and iOS 8 share a number of useful, common, features.