Squid 3.1 represents a new feature release above 3.0.
This version is however still in release candidate testing cycle.

The most important of these new features are:
* New Version Numbering System
* Minimal squid.conf improvements
* Native IPv6 Support
* Error Page Localization
* Connection Pinning (for NTLM Auth Passthrough)
* Quality of Service (QoS) Flow support
* SSL Bump (for HTTPS Filtering and Adaptation)
* eCAP Adaptation Module support