Absolute requirements
Must be able to set a schedule to post pre-defined tweets at predefined times and dates, including tweets with pictures, and tweets with videos.
Must be open source.
Strongly desirable
Should be written in one or more of: PHP, python, ruby, javascript, fortran. And so it's pretty much agnostic as regards operating system. If it's in some other language, then that should be one that compiles / runs on Windows and/or *nix.
Nice to have, but could easily do without
A nice interface to schedule tweets. But I'd settle for doing the scheduling by editing a text file.
