This article seems to focus on spreading FUD about HP printers. The truth is that most network-enabled printers have similar web interfaces and system administrators need to be diligent about securing them if they are going to attach them to a network. This is nothing new and it's not specific to HP in any way. Most any printer with a web interface, including many (all?) of the ones showing up in that Google search, offer mechanisms to require a password to access them. They also usually offer SSL to protect the passwords from packet sniffing, but a good systems administrator should not even allow their printers to be visible beyond their firewall. If they merely spent the time to set a password on the web interface, then Google would not index them.
The link to the web listener is merely the documentation on configuring the network settings for an HP JetDirect printer. You'll find something similar for Brother, Canon, Epson, Ricoh, etc. The last link about an unpatched JVM is complete misinformation. The link points to an article about Java's latest vulnerability being patched, but I've searched online and can find no evidence that any HP printers actually run Java. The best I can determine is that they are referring to the HP LaserJet Toolbox which is an embedded Java Applet on some web interfaces for LaserJets. There is no need to update the firmware on your HP printer for this. The security vulnerability there would be in a JVM running on the computer that you are using, not the printer, and that JVM is fully upgrade-able and can even be removed if your concerned about Java.
The only real news here is just how many system administrators have left their printers exposed to the Internet without a firewall, and, on top of that, have not bothered with even basic security on their devices like setting a password on the web interface and mandating HTTPS to secure their printers.