These snapshots are created automatically each night when there are changes. Each version can be downloaded in tar or zip format as well as its source code. The dates are the time that the version was created and can be used to judge the freshness of the release, you would normally download the top one unless you know it has a problem.
|mkgmap-r2606||[.tar.gz] [.zip] [src]||May 13||09:15||2.7M|
|mkgmap-r2520||[.tar.gz] [.zip] [src]||Mar 7||23:31||2.7M|
These jar files are latest builds of recent development branches. They are useful if you want to quickly test a branch without having obtain and build it. The source code is available via subversion.
As this is an automatic process, some of the branches might be already merged with the main line, or abandoned and of course they may not work.