Eh, whatever... the same thing happened with Batman Begins, and fake plots, or over-exagerated plotlines. Remember the rumors that half the film was taking place in London that never panned out? Yes, the rumors of the movie taking place outside of Gotham were true to a certain extant, but only in the first 45 minutes of the movie, before Bruce became Batman... and none of it took place in London. There were also rumors that it would follow plotlines from Batman: Year Two (which, other than the death of Joe Chill, never panned out either). This led to people assuming that the Reaper would be in the movie. I think there is some truth to every rumor we've heard so far, but I'd be very surprised at this point now if the Penguin, or Black Mask were going to be in the film. One thing you guys have to remember is that the Black Mask rumor went hand in hand with the Penguin rumor, and I haven't even heard a peep about Black Mask, or any rumors of who might play him since that first report, yet everyone and their sister has been named for a small cameo as the Penguin. From what I gathered from the report, Black Mask was a pretty hefty role, I'd assume we would have heard something by now if he were in it.
Oh, and as for the Penguin being in Batman Begins, he wasn't unless David Goyer and Christopher Nolan never did their research. The Penguin has always been locked up in Blackgate Prison (or Stonegate if you prefer TAS continuity). He's never been in Arkham, because the Penguin isn't crazy... he's just a criminal.