New Harry Potter film delayed by 6 months

The 6th installment of Harry Potter was supposed to release in cinemas on the 21st of November, but as you must have gathered by the title of this post - it's not going to :]
The film is ready and the producers are happy with it, but they think they'll earn more money if they release it on the 17th of July. This perhaps would not be so weird if they hadn't already released a trailer that says "November". Clearly this was a last minute decision.

So everyone is speculating what is the *real* reason for Warner Bros moving the dates.
There seems to be a hint of it in what Warner Bros have said:
Like every other studio, we are still feeling the repercussions of the writers strike, which impacted the readiness of scripts for other films — changing the competitive landscape for 2009 and offering new windows of opportunity that we wanted to take advantage of
In other words, because of the writer's strike they have no big hit to put up during the summer (the time of biggest box office earnings), so they decided to make Harry Potter a summer release.

Some are reading even more into this... The next Terminator with Christian Bale was supposed to release May/June. Does this mean Warner Bros think it will be a flop?

Another thought I had is that now that Daniel Radcliffe is doing Equus again (this time on Broadway), he might have had less time to do promotion for the film in autumn. With the first films the promotion for Harry Potter was focused on the whole trio and on quite a bit of the supporting cast too, but more recently Daniel Radcliffe has been doing the majority of it (I think very well - as you know I'm a fan of Daniel Radcliffe doing promotion on talk shows etc. ;-P), so I wonder if Warner Bros freaked out a bit with that too. There's less talk about Harry Potter now that the books have come to an end, so they may feel they need the promotion to be very strong.

Finally, I thought I'd share a silly clip of Harry Potter fan reactions to the date move ;)