From Adam:
"This version of Zoner's Half-Life compile tools offer many improvements over the original map compiling tools for Half-life, such as better lighting quality, faster vis times, switchable texture based lighting, support for brush entities casting shadows, removal of "sticky" edges, and much more."
ZHLT 3.2.1 was released on 14th March 2004.
Previous versions of ZHLT and XPCagey's tools are also available.