Don't worry, that bug will be fixed in TheNextRelease?, which will be out RealSoonNow. -- RobertField
Several years ago, in (I think) comp.lang.lisp, Lisp luminary Scott Fahlman posted this, which contains my favorite definition of the term:
I have to interject that this is a CatchPhrase? often seen by JerryPournelle in ByteMagazine whenever he has a prediction to make. RSN == RealSoonNow has become a BuzzWord throughout the InterNet. -- ChrisGarrod
I've always used it to mean: NotNowMaybeNever?. -- KyleJerviss
The best explanation for "Real Soon Now" I've ever seen is: "Soon, possibly never." We want to have it done soon, that really would be best, we'd all hope that would be the case, but, life being what it is... wear a helmet. -- BenScott
10 When's that? 20 RSN. 30 When's that? 40 Real soon now. 50 GOTO 10
See also: AlarmBellPhrase, LiterallyMeaningFiguratively