I had fun at the Nuit Blanche. I'll put together a longer post with lots of pictures over the next day or two, but since it's 6am and I want to get some sleep, I'll just post this quickie.
When was this photo taken?
(I've scrubbed the EXIF data in case any of you want to be cute)
For bonus points, where was this taken?
UPDATE: Alex gets it right below, and I'll just quote him: "Assumung 24:00:00 is midnight, then 28:00:00 would be 04:00:00 and 28:58:20 would be at 04:58:20, which means that if the metro left at 04:58:20 and there are 00:02:40 left before departure, the current time is 04:55:40 (AM)"
Some background: These are clocks installed at every terminus to tell the train driver when to depart. The top number is the time of departure, bottom left is the number of the train, and bottom right is time remaining to departure (it counts down to zero and then counts up until they reset it for the next train).
For scheduling purposes, the STM's daily clock doesn't reset at midnight. As far as bus and metro drivers are concerned, there are departures at 25, 26, 27 and 28 o'clock instead of 1, 2, 3 and 4am, as these departures (of day and night buses) are considered part of the previous day. You can even have two schedules running simultaneously if a night bus and early morning bus are on the road at the same time.
What's so unusual about this sight, of course, is that trains don't normally run at 4am. The last terminus departure is at 1:30am on Saturday nights on the yellow line. The last train leaves service 25 minutes later when it arrives at the Côte-Vertu station, making it 1:55 am or 25:55. Seeing the clock go up to 28:58 pushes it to new heights. (For those curious, the clock reset itself minutes later to 5am.)
Christelle got the second part of the question right (without getting the first). The picture was taken at Snowdon on the Saint-Michel-bound platform.