The $100 laptop (also known as the OLPC--One Laptop Per Child project) is not based on Squeak. It's partly based on Linux (the OS), but the stuff users see is largely written in Python. Squeak is on the laptop as one of the things students can use. I think the main reason it was put on there was for its eToys facility, which allows kids to draw objects on the screen and then program them to do things, to create their own simulations. It also has some games that run on it.

It's on there as part of the open source spirit of the system as well. Since Squeak reveals all of its code in Smalltalk, once they learn the language they can explore it and modify it however they like. The same goes for the Python stuff.

Re: Croquet

Yes, Croquet is written on the Squeak VM. It's actually based on a modification to Squeak, called "Tweak".

IMO Smalltalk is worth checking out. I've been doing so. There are different paths you could take with this. The basic level you can explore is the Smalltalk language itself. There are online books on the language you can read. There are some hardcopy books that cover the higher levels of Squeak. There's Morphic, which is the window manager for the Squeak desktop environment. There's eToys, which is a more abstract, but easy to use, scripting environment. Then there's Seaside, which is a web application framework for it. There are no books for this. The best source I've found for it are blogs that focus on Seaside.

Seaside uses some advanced programming constructs to create a programming environment that's unlike most other web frameworks out there. I haven't used it directly yet, but from what I've read about it, it's really nice. If you get into it you probably won't want to go back to what you used before.