What is monkey-patching?

In German! http://www.dzug.org/Members/Raphael/MonkeyPatching , English Translation

No definition yet: http://www.google.com/search?q=define%3A+monkey-patching :-(

Zope Monkey Patching

Examples & Notes

http://www.zopezen.org/Members/zopista/1023162757/view

Thoughts on Zwiki monkey-patching by Jeffrey Shell link