SqueakMap is a Squeak package meta catalog - a catalog of all available Squeak packages.
One master instance of the SqueakMap lives on this server. Then each Squeak connected to the Internet has a slave instance of the map that is synchronized against the master. This way every user can have an updated catalog of all available Squeak software on the planet. :-)
A SqueakMap contains:
The packages and package releases are owned by the accounts. The categories are maintained by a selected few SqueakMap administrators.
The central master SqueakMap has a web UI but activities like searching and installing packages are typically done by using a synchronized slave master map living as an object model inside your own local Squeak image. The slave map always keeps the state in a single file on disk and can synchronize itself with the master map by using a single gzipped HTTP request.
Read more about SqueakMap on its package entry in SqueakMap.