I was at the Flash Memory Summit moderating a PC design panel and after listening to several vendors and a storage analyst (who has posted on flash in enterprise storage products), I've concluded the answer for now is no. The problem is that they simply don't yet provide enough advantages to overcome a massive price premium.
The power differential is between 1 and 2 watts, but given how much power the rest of a desktop or laptop uses, this is trivial. On reliability, yes, they will survive better than a hard drive if the system is dropped, but their reliability really isn't that well known in general use.
If they are designed well, they can last between three and five years, but I'm not aware of anyone providing the necessary gas gauge-like tool that would warn you that it is wearing out. While you could use a TPM to secure the device, no one is yet doing that, which means the new secure drives out of companies like Seagate are much safer. Finally, in terms of performance, the random read performance out of these drives (compared to linear read) is horrid. This takes what otherwise would be blinding performance advantages and turns them into slight advantages on system boot and first-time application load.
Indications are that the gaps will likely close in the 2010 to 2014 timeframe which, to me, means that at least for PCs this technology is off the table as a practical alternative to hard drives until then. This is all primarily due to the fact that flash drives cost between five and 10 times as much as a similar capacity traditional hard drive.
Recall that hybrid hard drives, ready-boost drives, and Intel's Turbo Memory have all failed to gain traction; flash is in real danger of being a non-player in PCs over the next several years unless some of these shortcomings, especially price, can be overcome.
Where they do work is in ultra-thin laptops, but I still wonder if the extra $1,000 cost of these products is really worth the bragging rights of having something that thin. The reason they do work here, though, is that the iPod drive alternatives are really slow and folks tend to actually want to work on the laptops they buy. Personally, I think a slightly thicker laptop seems to be a better alternative.