The Carnegie Mellon University Sieve implementation was initially released in January, 1999. It's now part of the Cyrus IMAP server. ManageSieve has been implemented as part of the CMU Cyrus Sieve suite.
Citadel is a tightly integrated, easy to install, open source groupware platform. Sieve support began with version 7.00 of the system. Normal users can have Sieve scripts auto-generated when they use a web-based rules editor. Advanced users can compose their own Sieve scripts and enter them using the web interface or the managesieve protocol.
DBMail is adding support for Sieve and ManageSieve.
Isode M-Box includes support for Sieve, which is thread safe version of Cyrus Sieve. ManageSieve has been implemented as part of the Isode M-Box suite.
Apache JAMES project can use the JSieve component. JSieve is a language processor that can also be plugged into any internet mail application to add Sieve support.
mvmf is a delivery agent currently in use, and still under active development. Its scripting language includes an embedded Sieve implementation.
Newer versions of PMDF from Process Software have Sieve support via a web-based interface.
RockliffeMailsite v5 supports server, domain and mailbox level Sieve filtering with a rule based windows GUI, and a slightly limited web based GUI. A trial version can be downloaded from the web site.