A: Yep. :-)
Q: But what keeps some psycho from just deleting everything and destroying it?!?
A: These are probably the two most frequently asked questions by newcomers to the Wiki World. The short answer is: "Not too many destructive psychos seem to use Wiki, and even if they did, the Wiki software keeps records of every change made on the Wiki site, and uses VersionControl? to allow you to compare-with, view and roll-back-to earlier versions of pages, and undo any damage done. The length of time that records are kept varies from Wiki to Wiki. Some keep only the last 2 changes, or the last 2 days. This Wiki keeps [an entire year of records], so even if someone deleted something maliciously (please don't), we could fix it.
And anyway, the Wiki community itself can keep an eye on things and (hopefully) catch and fix up problems before they get out of hand. Since everyone can edit just about everything, you have the power to undo any vandalism that someone else might commit.
If you're interested in learning more about this admittedly odd concept, you should read the following:
There are many more pages linked from those, if you want to get deep into the philosophy of it.
Q: OK! This Wiki stuff seems pretty cool. Where can I find other Wikis?
A: One place is the UseMod:SiteList, which mainly lists sites running this "flavor" of Wiki Software. There are others, though, and you'll probably find links to them as you wander through.