Do these things infect all types of computers (PC and Mac)? I went to that site as well and my browsers have been acting up.
While any computer can be infected by a trojan (a program masquerading as something else that trick users into installing and running them) written for its operating system, some OS are much more secure than Windows.
The Mac OSX is one of those more secure operating systems. As of this writing there only a couple of trojans concept program written and none have been observed in the "wild". Macs are immune to most viruses and worms as getting them to download, install, and execute a malicious program is extremely difficult if not impossible.