I have been following this lightly for a while. On the one hand
Rossi's history does not give confidence to this being real. On the other hand he doesn't seem to approach it like I would expect a scammer to approach it - he does get in touch with universities and professors, and he does not ask for money, even apparently financing the contruction of this 1 MW plant himself. Also holding a large-scale demonstration with big-name media present does not seem usual. If it is a hoax, I am not sure what he would get out of it besides publicity (being in the news).
There are 3 options: (1) it is a hoax/fraud, (2) he really believes it is true and cannot manage to do measurements correctly or is in some kind of denial and interprets the results incorrectly so they fit his beliefs, (3) it is true.
It is not clear whether this demonstration will make it clear. There have already been
11 other smaller-scale demonstrations and apparently there has never been conclusive evidence throughout all these. It also depends on who is vetting the test. There is someone from PESwiki there
tweeting updates, tweeted "Q&A just finished; reading of results; 470 kW maintained continuously during self-sustain; customer satisfied; sale made; more later." and expects to post an article on the wiki/blog in the next hour or so. PESwiki historically has followed/reported on hundreds of bogus technologies. But the customer is satisfied? Who is the customer!
Also an AP writer from NY is apparently attending the demo. However, a link to the likely writer says that he covers "telecommunications, consumer electronics, etc" for the AP, so it's not likely he is knowledgeable about energy technologies.
It will be very interesting to see the reports.
Here are the various semi-high-profile news articles about this technology that have recently been published, to collect them all in once place:
Forbes blog, Oct 28th
Wired, Oct 28th
Forbes blog, Oct 17th
Wired, Oct 6th
And then plenty of other sites like blogs and physorg since January of this year.