Basically, Nortel (in bankrupcy) sold 666,624 IPv4 addresses to microsoft for $7.5 million, i.e. $11.25 per IP address.
That is mad!
Now, it could be iffy reporting of course. RIPE, for example, allow transfer of IPs if you can justify them. Right now, if you can justify them, you can have new IPs as the registries have not quite run out. So why would anyone pay for IPs just yet?
Of course, they probably buy the company and the company has the IPs, and so do not need to transfer them at the registry as such. That way they get to buy IP space that they could not in fact justify (on the short period registries require) but will last them a while. No idea if that is the case here.
Even so, if this sets the bench mark, before IPs have run out at the registries, surely the price can only go up once they do? What will be fun is how quickly those IPs lose value when IPv6 starts to properly take a grip.
Oh, and we have over 100,000 legacy IP addresses... Hmmm.