"Homefront Six" has an account of her May 2006 visit to the Gamble House on her weblog. Especially notable are the photographs, some from the official Gamble site and some, I think, which she must have snuck in during her tour - they don't allow you to take pictures, but of course plenty of people do anyway. And as far as no flash is used (flash can certainly damage textiles and other surfaces in the house), I doubt anyone would be severely castigated.
Japanese blogger Minabako also visited the house not long ago, and if you read Japanese you can review her experience as well.
Matt Jalbert developed and maintains the Gamble House website; his own weblog includes some fantastic images of the exterior that capture the late-afternoon light better than any I've ever seen.
The Spurious Plum has visited the Gamble House and several other G & G properties in the area, and includes several photographs in her report.
Finally, "Ridiculous Authenticity" visits the Gamble House and writes a bit about his / her visit in an article titled "misadventures in architechture," which does not apply to this particular property.