From Dan Grayson:
Version 1.8.1 of Macaulay2 has been released, and distributions for various architectures are available on the web site at http://macaulay2.com/. The source code is also available in the downloads section, if we don’t have a release for your architecture.
This is a minor but recommended update to 1.8, whose release suffered a minor glitch, and was available only briefly. The lists of changes is available onthe web site.
Speaking of Macaulay2, we here at commalg.org have hosted since 2002 (!) a page about installing M2 on Windows. It is now out of date in every possible way, and we will be retiring it in the near future. If you know of some reason this is a bad idea, please get in touch with us as soon as possible.