Definitely affects trunk, most likely affects other versions too, but I have not checked.
To reproduce you need to set different time zones in php.ini file and system-wide, system time zone must be ahead of PHP date.timezone, for example:
Then go to Configuration->Maintenance and press Create maintenance period.
Press the little calendar button next to Active since or Active till settings.
P.P.S. Strangely, this calendar selector is used in many places across frontend (e.g. in graphs and screens), but only maintenance form seems to be affected.