I think it would be very handy to have something like device.ontime(yr,mo,da,hr,min,sec) to trigger an event at an entered time. If the more significant date parts are left blank the function would assume the current value of those parameters. For instance device.ontime(12) would trigger on second 12 of the current minute (if it hasn't already passed). Whereas device.ontime(27,36) would trigger at minute 27, second 36 of the current hour (if not already passed). It would be a variation of imp.wakeup that is tied to a fixed time rather than an elapsed time.
Of course, depending on time stamps would limit to +/- 1 sec. which would generally be okay for the type of applications I envision.
This functionality can be implemented in code, of course. But it would be a nice feature.