Benjamin Melançon's blog

• Ask.com (Teoma) does cache, but very few of its pages
• Yahoo (Inktomi) caches
• MSN Live Search (also used by A9) for all practical purposes does not.
• Google does cache nearly everything
• AllTheWeb.com doesn't have a cache
• Altavista doesn't have a cache

Useful page page:

http://www.antezeta.com/search-engine-cache.html

Dangers of widespread proxy caching (which is distinct from caching for archive or index purposes):
http://www.isoc.org/oti/articles/0198/tewksbury.html

Yes, openzuka has set itself the audacious goal of replacing google as the dominant search engine. We need the help of programmers of course, but we also need the help of promoters and people who just know what they want in a search engine.