No apologies to using a hackneyed paraphrase. This is a hackneyed subject, no matter what. When I first saw the original article appear, my first reaction was "what a pack of eedjits!"
I haven't changed my mind, either. Let's assume, for this scenario, that black backgrounds really do save energy. (They don't on some monitors, by the way.) So how long do you typically spend on the serach engine results page? An hour a day in total? That's under 5% of the day. Assuming that your monitor uses 20% less power on that black screen, that's a saving of 5% of 20% of total power use, or 1% power saving. I could save that by hitting keys slower when working, so that my body doesn't produce as much heat load for the air conditioner to have to move...
Then too, the penetration of LCD monitors means that the backlight stays on at the same level, and switching pixels to black could actually increase power consumption. Also, on some older tube type monitors, clamping the EHT power supply down rather than switching it off can sometimes be used to produce black. Again, those monitors actually use more power when displaying black.
And of course, while the penetration of LCDs is estimated at 75% in the Google blog article, most of those are in a work environment, many home computer users still have tube type monitors. So the work related monitors are at best not going to experience a practical difference displaying black, and besides, most workplaces pretty much discourage keeping a search engine with a black background open instead of a crisp white document, so these will typically spend much less than an hour a day with that page on top, anyway.
And the homes users, they may use a search engine, but only to find new crisp white pages to read and crisp white games to play.
Best way you can save energy with your monitor is to turn it off when not using it.