SigCPerl is a Perl wrapper for the libsigc++ signal library. It can be used to provide stand-alone signals, but is intended to provide a mechansim for writing Perl modules which wrap other C++ libraries which use libsigc++.
You can get the source either from the download page, or directly from CVS. You need two separate pieces, a helper library called sigcperl, and a Perl module called SigC. There is also a test module called SigC::Test, which may give you some ideas about how to use the library.
All this and more is available on our sourceforge project page.