Well, after reading this thread, I went and tried it on my broom. Guess what? It stood up all by itself!
My location is the west slope of the Cascade Mt. range just east of Seattle and up near Snoqualmie Pass.
I've tried this before and could never do it but I did it just now and I wasn't trying to spread out the bristles or anything.
This happened once before around the time oddly enough back in Nov. 2004? I was sweeping all the fir needles that were tracked in from the garage (this is a problem in the PNW, the fir needles get everywhere!) and after I was done sweeping them into a heap, I let go of the broom misjudgeing where the wall was behind me as I was in a hurry to go get the vacuum cleaner. When I came back, I saw that the broom wasn't even close to the wall. It was standing all by it's lonesome. Pretty weird.
I just took a pic on my cell phone to show my sister tomorrow and a vid where I panned up and down the broom to prove I didn't spread the bristles out.
I have often wondered back then on exactly why the broom stood up by itself and the only thing I could think of was that after all that sweeping, the bristles built up a good static charge and with the handle being metal, maybe it had some type of magnetic action going on, some type of small 'field effect' around it?
But seeing that there was a very strong magnetic storm back in Nov. of '04 and one just happened, the atmosphere must be pretty charged up and this may be why brooms all over the place are standing by themselves right now? It's a thought...
I just thought of something, this reminds me of the Oregon Vortex which I've read about but have never been too. It's in Gold Hill, Or. Here is a link to the place.
http://www.oregonvortex.com/science.htm
They have a neat explaination for the effect. V
Edited to add... I just googled 'oregon vortex broom standing by itself' and found a link with a pic of one doing what all of ours is doing right now. Check it out!
http://www.roadsideamerica.com/story/29062