Did it mix? Your brake fluid should be yellowish (depending on the brand, but most commonly available fluid is the color of pee.).
Keep in mind, brake fluid is hydraulic fluid, same as your power steering fluid. This doesn't mean that damage is not being done however. The hydraulic fluid could be eating up your brake seals as you read this.
I'm inclined to believe that the ps fluid is still in (or very near) your master cylinder still. It would be unwise to open a bleeder screw on a brake caliper and attempt to flush it out. I'd think that would force this fluid into other parts of your braking system.
You may try to siphon it out of the master cylinder reservoir. I use a short length of clear tubing, inserted in a hole poked in a clean plastic soft drink bottle. Squeeze the air out of the bottle and put the hose end in the reservoir. It'll do a decent job of pulling out fluid without contaminating it. When you're done, just swap out the drilled cap with a good one and toss it away.
I can't think of too many fluids in a car that are more corrosive than brake fluid -so I don't think that the addition of the p.s. fluid will hurt anything, but I would try to get it out of your braking system asap anyways.