Google has a bit of a grace period on 404s, where something that used to exist will still turn up in search results after it's been removed by the owner. But, eventually, those results will disappear too, and it will vanish from existence...

The Wayback Machine is your best bet for old content, especially if you know what URL you're looking for, but if it's something that's only been recently created it may not turn up there for a time.

Oh, and Google or Bing's cache of a page (as linked to from a search result) MAY return the content you're looking for, but I've noticed that's been more miss than hit lately (no cache links, cache link can't be found, etc.)