Electronic voting has been implented using the DEVote system, written in PHP and using a MySQL database. It is available for download under the GPL.
DEVote II - a new version written in Kaya with support for MySQL and Postgres databases, as well as many new features and a much easier installation process, is currently under development. You can see the current state of development at the test installation - comments welcome.
Counting by the Single Transferable Vote method takes place by two programs. DEVote now has an inbuilt STV counter, but there is also the Beremiz program (Beremiz Javadoc documentation) , which is written in Java and produces count output more suitable for reading into vote graphing programs.