I've been reading Order of the Phoenix (yes, some of us can't afford those big-time hardback editions) since its just come out in paperback. Some thoughts...
I know JK Rowling is a progressive who pays attention to current events. It seems like Order is a dead-on allegory for the war on terror. Some examples:
Harry Potter claims Voldemort has returned and no one believes him
The press (the Daily Prophet) seek to paint Potter and everyone who agrees with him as crazy or inept
The Ministry of Magic is spying on students and teachers and interfering in the curriculum of Hogwarts
The central debate between the warring factions is whether only those of "pure blood" should be educated in magic and whether wizards should seek to attack and/or rule muggles (non-magic people) since they believe themselves to be "superior"- the evil ones obviously believing those things.
There is a great article here summing up some other ideas on this:
http://gnosticalturpitude.org/archives/000218.html
The best piece is that Harry Potter is infused with progressive ideals and values- and that millions of kids are reading it.