I was only just watching a trailer for the next GIJoe movie last week when seeing Avengers, as it was scheduled for release in a months time.

Today though, at the last minute (and at the surprise to the Director himself), Hasbro have pushed it's release back 9 months to March 2013.
Their excuse - they only just decided to retrofit it to 3D, to cash in on a growing popularity on the format (perhaps it was expected to be a short-lived fad).

Even the toys were already in US stores, ready for its release in theaters, so I'd imagine a lot of US retailers are not happy about having stock that won't move for another 9 months.

Hasbro Australia are probably glad they didn't have the headache of dealing with angry retailers, and sitting on later waves that stores wouldn't be wanting for another year. All those toys not yet in stores would have already been made, and waiting to go to retailers.

Having a 3D version should have been decided early on, and stuck with it. (which was something Michael Bay was at least good at - deciding to use the format, and committing to it)

I feel bad for the GIJoe fans who were looking forward to the movie in five weeks time, only to now have to wait almost a whole year for it.
Imagine if that had happened with one of the Transformers Movies...