=~ operator now indicates bounding box equality, not feature equality
GEOS 3.1 is now the minimum accepted version of GEOS
GEOS 3.2 is needed if you want to use enhanced buffering features and ST_HausdorffDistance
GEOS, LibXML2, and Proj4 are now mandatory dependencies

New Features

Added Hausdorff distance calculations (#209) (Vincent Picavet)
Added parameters argument to ST_Buffer operation to support one-sided buffering and other buffering styles (Sandro Santilli)
Performance improvements to ST_Distance (Nicklas Avén)
Addition of other Distance related visualization and analysis functions (Nicklas Avén)
ST_ClosestPoint
ST_DFullyWithin
ST_LongestLine
ST_MaxDistance
ST_ShortestLine
KML, GML input via ST_GeomFromGML and ST_GeomFromKML (Olivier Courtin)
Extract homogeneous collection with ST_CollectionExtract (Paul Ramsey)
Add measure values to existing linestring with ST_AddMeasure (Paul Ramsey)
History table implementation in utils (George Silva)
Win32 support and improvement of core shp2pgsql-gui (Mark Cave-Ayland)
In place 'make check' support (Paul Ramsey)
Geography type and supporting functions
- Spherical algorithms from Dave Skea
- Object/index implementation from Paul Ramsey
- Selectivitiy implementation from Mark Cave-Ayland
- Serializations (KML, GML, JSON) from Olivier Courtin
- ST_Area, ST_Distance, ST_DWithin, ST_GeogFromText, ST_GeogFromWKB, ST_Intersects, ST_Covers, ST_Buffer
Documentation updates and improvements (Regina Obe, Kevin Neufeld)
Testing and quality control (Regina Obe)
PostGIS 1.5 support PostgreSQL 8.5 trunk (Guillaume Lelarge)
Many, many other changes