It's interesting
It's interesting to see this technology finally being developed. I will be curious to see how long it takes for it to catch on here in the US. I think it's initial market will involve some combination of several factors: those areas where it is difficult to install a vented dryer and those places that don't have piped-in natural gas where heating is done with electricty or oil.
In the US, the initial potential is probably in places like the Northeast where piped natural gas is spotty due to geography and electricity and oil are relatively more expensive. In that case it certainly makes energy sense to use a heat-pump dryer that will not empty out a house full of oil or electrically heated air while consuming a fair amount of additional electricity in the process. Now, considering that this technology will be considerably more expensive to manufacture than a traditional vented electric dryer it will be interesting to see where the "tipping" point is for the consumer. This is just a guess, but I would think that the price of one of these dryers would be in the $1500-$2000 range. That is not going to be commercially interesting to a consumer in a market where they have $.65 natural gas and $.08 electricity. However, in a market with no natural gas, $3.00 heating oil and $.20 electricity...we'll have to see.
One thing that I am very curious to see is the actual numbers concerning energy use, especially comparing the number of kw/hrs that this dryer uses compared to traditional electric dryer. It would also be interesting to see a chart that included the actual number of converted energy units used by a heat pump dryer, an electric dryer, and a natural gas dryer taking into consideration the amount of pre-heated home air (also via electricity, oil and nat. gas) that is vented out on say a 40 degree winter day by the later 2 dryers.
As Combo mentions, this idea has been floating around in many people's minds for years (mine included). His information is very good and clear.