As the great reporter that he is, Paul wrote up great summaries of Day 0 and Day 1 of the New York Code Sprint.
In addition to the MapServer 6.0 release plan discussions (brainstorming) that he already mentioned, I have been involved in several discussions here and there about MapServer and GDAL/OGR.
One of the main coding tasks for me yesterday was the extraction of the OGRSpatialReference code from GDAL/OGR into a standalone libOSR package that currently sits in a sandbox in GDAL's SVN repository. This libOSR package will be useful to libLAS, PostGIS, and other packages that need SRS conversion utilities but don't want to carry a complete copy of the GDAL library.
On the menu for me today: some experiments to support on-the-fly conversion of XML mapfiles to text mapfiles inside MapServer using the XSLT, and then possibly start looking into SVG symbol support.