From PostgreSQL wiki
A CommitFest (CF) is a periodic break to PostgreSQL development that focuses on patch review and commit rather than new development. These are held so that all the work for a release gets relatively prompt review and feedback, and so that work for a release doesn't pile up until the end of the release cycle. During these periods developers are asked to review and test the patches submitted by others. The hope is that this will also reduce the burden on those who do the final review and commit. The CF page is used to keep track of submitted patches and their status, to help manage the process.
When we're not trying to put together a major release CFs tend to run for one month each with a one month gap between them. Due to the process of getting a release out the door, though, there may be several months in a row without such a review cycle. After such a hiatus the first CF may be immediately preceded by a review-only phase before committers are able to participate at normal levels; such a phase may be called a ReviewFest (RF).
A CommitFest manager arranges for all the submitted patches to be reviewed. The peer review process often results in discussion on the pgsql-hackers list and/or requests for some sort of modification before commit. Most patches wind up getting committed, although some are returned with feedback (in hopes that the submitter will make some change and submit to a later cycle) or rejected (if they are determined by the community not to be useful changes). Once complete, a new Alpha release is produced for testing; after the final CommitFest for a release, a beta version is packaged.
The CommitFests are managed through our web application at commitfest application. Please submit/review/organise patches there.