What does that mean? Well, it COULD mean any number of things, from the relatively benign-- some kind of contract or deal fell through that postponed or cancelled the movie --to the more dire, that Madhouse is low on funds. I'm personally doubting the latter; Madhouse always seems to take care of itself, although it's possible that it's a temporary stop-gap measure taken while waiting for a check to clear, or something along those lines.
But I think the former, a contract or licensing issue, seems more likely. Again, just my speculation.
Now, what movie is it? It seems to me that the most likely victim is an unannounced project, since those are the easiest kind to shut down anyway.
There's a chance, of course, that it's the upcoming Trigun: Badlands Rumble movie, and I hope to god it's not, but that film opens in April so short of some real disaster I can't imagine why Madhouse would put it on hold a mere two months away from its opening, if it's even unfinished.
Satoshi Kon film Yumemiru Kikai, due out later this year, but the official blog for the film just updated on Thursday, so that doesn't seem too likely either (oh thank god).
So what's left? The only thing I can think of is the Siberian Express anime project, which isn't even announced to be a movie or a TV anime or anything yet, I think.
Or, again, it could be something that hasn't been announced at all yet. One more time, with feeling: this is all speculation on my part, folks! Now, go forth and speculate yourselves, in the comments. Which would you rather have to not see: the Trigun movie or another Satoshi Kon work?