Here is a list (in-progress) of the things needs to get Sage to build (and pass most tests) on Cygwin:

* #8257: gd needs a better version of expr

* #7319: gdmodule fails

* #7321: numpy fails to build on cygwin due to not using the correct fortran compiler

* #8780: Add cephes spkg for Cygwin (provides complex.h amongst other things)

* #8192: PolyBoRi needs png12 and z to build on Cygwin.

* #8782: pari does not work under Cygwin

* #8907: Python should be build with enable-shared

* #8278 / #6456: cvxopt does not work in Cygwin

* #9050: libntl.dll should be libntl.dll.a

* #8542 / #8903: Pynac needs to use a function pointer table.

* libflint.dll needs to be libflint.so, or polynomial_integer_dense_flint.pyx needs to know to use the .dll (maybe not a real issue, let's wait an see on this one).

* Use ECL from #8645 and Maxima from #8645 or #8731

* #8642: port detection for the notebook does not work in Cygwin

* #8855: sage-env needs to be updated for Cygwin

* #8853: fix M_PI_4 in complex_double on Cygwin

* #8852: minor doctest fix in fast_eval.pyx for Cygwin

* #8850: Cython should link against BLAS instead of ATLAS on Cygwin

* #8849: the palp interface throws a (harmless?) OSError on Cygwin

* #8848, #8847, #8846, #8845, #8844, #8843


Possible issue with Python 2.6:

http://groups.google.com/group/sage-windows/browse_thread/thread/88499b995a22ecc1

(I had no problems with that thus far in Vista Premium 32-bit -Alec Mihailovs)

(Alec - Win7 has a newer codebase, so this is not really a proof that we need not worry --- I think we really need to. Dmitrii)