The changes are fully described at
http://trac.osgeo.org/gdal/wiki/Release/1.8.0-News
However, the following are the highlights.
In a nutshell:
* New GDAL drivers : GTX, HF2, JPEGLS, JP2OpenJPEG, JPIPKAK,
KMLSUPEROVERLAY, LOS/LAS, MG4Lidar, NTv2, OZI, PDF, RASDAMAN,
XYZ
* New OGR drivers : AeronavFAA, ArcObjects, GPSBabel, HTF, LIBKML,
MSSQLSpatial, NAS, OpenAir, PDS, PGDump, SOSI, SUA, WFS
* Significantly improved OGR drivers : DXF, GML
* New implemented RFCs:
o RFC 7: Use VSILFILE for VSI*L Functions
o RFC 24: Progressive data support in GDAL
o RFC 28: OGR SQL Generalized Expressions
o RFC 29: OGR Set Ignored Fields
o RFC 30: Unicode Filenames
o RFC 33: GTIFF - Corrected !PixelIsPoint Interpretation
* New utility : gdallocationinfo
Backward compatibility issues:
* MITAB driver: use "," for the OGR Feature Style id: parameter
delimiter, not "." as per the spec. Known impacted application:
MapServer?
* RFC 33 changes the way PixelIsPoint? is handled for GeoTIFF
* GML driver: write valid <gml:MultiGeometry> element instead of
the non-conformant <gml:GeometryCollection>. For backward
compatibility, recognize both syntax for the reading part