Yes, Angelo deserves a lot of kudos for his efforts, but unfortunately
much more is needed. For example, even though it is possible to build
a Cygwin version now, if you are willing to install specific versions
of development tools, the following entry from etc/PROBLEMS in the
Emacs distribution would not sound very good to me if I were a Cygwin
user who needs to decide whether to install Emacs:
*** Building the Cygwin port for MS-Windows can fail with some GCC versions
Building Emacs 22 with Cygwin builds of GCC 3.4.4-1 and 3.4.4-2 is
reported to either fail or cause Emacs to segfault at run time. In
addition, the Cygwin GCC 3.4.4-2 has problems with generating debug
info. Cygwin users are advised not to use these versions of GCC for
compiling Emacs. GCC versions 4.0.3, 4.0.4, 4.1.1, and 4.1.2
reportedly build a working Cygwin binary of Emacs, so we recommend
these GCC versions. Note that these versions of GCC, 4.0.3, 4.0.4,
4.1.1, and 4.1.2, are currently the _only_ versions known to succeed
in building Emacs (as of v22.1).
Feel free to update this entry for recent versions of GCC, but
personally I would stay away of a package that has problems with so
many versions of the compiler.