not ready for prime time
Usable, but only just so; not very robust; for internal use only. Said of a program or device. Often connotes that the thing will be made more solid Real Soon Now. This term comes from the ensemble name of the original cast of "Saturday Night Live", the "Not Ready for Prime Time Players". It has extra flavour for hackers because of the special (though now semi-obsolescent) meaning of prime time. Compare beta.