Lyft, the definitely-not-a-taxi service that is not Uber, is adding a useful feature: scheduled rides. This means exactly what you think, giving the option to call for a, well, Lyft for some future time. With that said, you probably can't use scheduled rides just yet as it is currently being piloted in San Francisco.
Assuming Lyft does roll it out to their other markets this summer as they say they will in their announcement, there will be some guidelines. The main thing is you cannot schedule your ride more than 24 hours in advance.
You can imagine how giving too much ability to schedule things out could lead to the service becoming more like flight planning than on-demand transport. Without a limitation on how far ahead of time you schedule, you could do something like buy concert tickets and schedule your ride home at the same time, months before the night in question. This would be cool, but is counter to the ethos of Lyft. That's because they seemingly don't want to risk having users routinely seeing all rides completely booked well beforehand.
Some added flexibility for Lyft users is that you are allowed to cancel or change scheduled rides as long as you do so 30 or more minutes before pickup.
It's clear from Lyft's announcement that they want people to still feel confident there will be on-demand rides available. They see scheduled rides as an addition, not a replacement, with some wording clearly targeted to drivers who may be looking for a bit more certainty in terms of their daily earnings. It looks to me like this feature will be a winner.
Scheduled Rides have now gone live in San Francisco.
According to a new post on Lyft's blog, this feature has now gone live in San Francisco. More cities are coming "soon", but keep in mind that back in May it was San Francisco that was coming soon.