Thanks for the Borge link, thalbergmad, I nearly split my shorts laughing.
I play a lot of chamber music (no, jinfiesto, we don't call it accompanying, we call it "chamber music") and it's pretty hard to memorize. Also, it's valuable to see what the string players are doing.
So page turning is a major issue. The Faure C minor Quartet I'm working on has 85 pages to the piano part!
What I've learned to do is to drop out a hand and flip, usually with the right hand. This can get stressful, and you must actually practice your page turns before a concert. Another option is to memorize a staff or two until there's a break and flip there.
We hired a page turner for several concerts, and yes, she was truly beautiful, smart, distracting and all that, but she bailed at the last minute before a concert so that ended that...Another turner couldn't read music, and it was a re-run of Victor Borge. Pretty funny, actually.
The Orion Quartet, I believe, has gone the digital/foot-mouse route, requiring a laptop and scanner. Works pretty well for string players, but a lot of work for the pianist. When I heard them play the Brahms Quintet with Peter Serkin, he used a page turner.
I dunno...At least from my point of view, you can usually drop out a hand for a beat or two, get 'er done, and no one's the wiser.