It has been six months since the last major release (1.7). During this period the Tiki team has grown from 68 contributors to 190!! Detailed stats here: TikiCommunity
For the last several months, Tiki has been eating it's own DogFood and using Tiki 1.8 on tikiwiki.org Three release candidates (over three months) later, the Tiki team is proud to release Polaris.
The main major new feature is a complete rewrite of all the queries to move to the ADOdb abstraction layer. This makes Tiki highly portable and useable with your favorite database. Tiki 1.8 boasts over 65 new features & enhancements. Congratulation to redflo for managing this release.