Heard, but hardly seen speakers aren't new.
There's a number of glass and clear plastic speakers on the market, but these fetching British models are something else again. People seem to want speakers and audio gear that "disappears" and still sound great. Ferguson Hill makes a full line of see-through designs, and from the looks of it the FH001 just might be a real contender.
It's a "horn" speaker made of clear acrylic, and its ultrahigh efficiency design allows it to play nice and loud with as little as 3 to 50 watts. So there's no need to use the FH001 with power hungry amplifiers! Horn speakers are easily the "greenest" of speaker types, and work well with even the smallest, most power-efficient amplifiers. I first heard about Ferguson Hill on the Ultimate AV Web site.
With a claimed frequency response of 150 Hertz-20 kHz the FH001 doesn't need separate tweeter and midrange drivers, most of the sound comes from one driver in the apex of the horn. Bass is the job of the FH002, a 24 inch acrylic sphere fitted with a 12-inch woofer.
A complete Ferguson Hill stereo system built around the FH001 and the company's matching electronics would run a tidy $26,000.
How's it sound? I have no idea, but based on my experience with similar designs, it'll probably be an acquired taste.