Both these effects rely on the jQuery Javascript library, which is just about the best Javascript library in the world. Forget "Spry" which is supplied with Dreamweaver. It's very clunky. Actually, if you are going to forget Dreamweaver (recommended) and if you mainly use PHP or Ruby to write your websites then you should try the Netbeans IDE or Eclipse. Both are free and in my opinion very much superior to Dreamweaver for scripting work.
As for entropy, well my simple take on this is that everything is slowly turning into a disorganised mess, and there ain't a thing we can do about it. So this site is called Cobblers because it's a disorganised ragbag collection of bits and pieces, and is a mess.
HTML5 & CSS3

Well - this is the NBT (Next Best Thing) right now ( Summer 2010 ). I've read a couple of books about it: Introducing HTML5 by Bruce Lawson and Remy Sharp and HTML5 Designing Rich Internet Applications by Matthew David. The latter book is, in my opinion a cynical attempt to cash in on HTML5 - it must have been written in about 4 weeks - max. It's littered with typos, spelling mistakes, atrocious grammar and technical inaccuracies. The book by Lawson and Sharp is much better. It's not as shouty and gives a dispassionate review of all the new features.
Custom 404

There's a customised 404 (HTTP protocol: page not found) error message on the site. To see it, just type in some url which does not exist on the site - like this one (cheese.html) for example.
Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Quisque sed felis. Aliquam sit amet felis. Mauris semper, velit semper laoreet dictum, quam diam dictum urna. Suspendisse quam nisl, placerat vel suscipit vitae, ornare a elit. Nunc volutpat nibh blandit tortor gravida ut porttitor nunc ullamcorper.
What's Lorum ipsum ?

Lorum Ipsum is meaningless, mock-latin. It's used simply as a place holder for text, during the design and building of a web site. There are many sites (here's one) which will generate pages of the stuff for you.
Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Quisque sed felis. Aliquam sit amet felis. Mauris semper, velit semper laoreet dictum, quam diam dictum urna.
You'll see quite a lot of Lorem ipsum if you wander around this site !