[disables]

Bitcoinica.com has an invalid DNSSEC configuration and is not reachable for users with DNSSEC validation enabled (this is known for a few weeks).
Most ISPs do not validate DNSSEC, but a few do, like Comcast. Comcast set up a temporary exempt to allow DNS resolution for bitcoinica.com despite the DNSSEC validation failure. This exempt will be removed on Tuesday, May 29 (http://www.dnssec.comcast.net/). Thus, bitcoinica.com will be offline for Comcast users.

Test here if your DNS resolver validates DNSSEC signatures: http://dnssec.vs.uni-due.de
If the result is YES, then you're either a Comcast customer or you already can't reach bitcoinica.com (like "Could not locate remote server").

Solution: Bitcoinica has to login at their registrar and remove the two erroneous DS records (see dnsviz.net)

Workaround: add 8.8.8.8 as DNS server in your network configuration (this disables DNSSEC validation – make sure you want this).

Hi,

I'm holding a talk about Bitcoin in a couple of days. Target audience are computer scientists and it's focused on technology.

http://dl.dropbox.com/u/212148/bitcoin-talk.pdf

Any corrections appreciated.
I'm also preparing some backup slides about recent hacks, Namecoin and why non-scalability isn't the end of the world.

Regards,
Theo