There are many improvements and new features in Privoxy 3.0.4 :
Mulitiple filter files can now be specifed in config. This allows for locally defined filters that can be maintained separately from the filters as supplied by the developers.
There are a number of new actions:
In addition, fast-redirects has been significantly improved with enhanced syntax.
And hide-referrer has a new option, conditional block.
MS-Windows versions can now be installed and started as a service.
In addition, there are various bug fixes and significant enhancements, including error pages are no longer cached, better DNS error handling, and various logging improvements.
A quick list of things to be aware of before upgrading from earlier versions of Privoxy:
Some installers may remove earlier versions completely, including configuration files. Save any important configuration files!
See the full documentation on fast-redirects which has changed syntax, and may require adjustments to local configs.
The jarfile, cookie logger, is off by default now.
What constitutes a "default" configuration has changed, and you may want to review which actions are "on" by default. This is primarily a matter of emphasis, but some features you may have been used to, may now be "off" by default.
Some installers may not automatically start Privoxy after installation.