Page Cloaking / Code Swapping

Earlier, I have heard of few ways of spamming: keyword stuffing, hidden text and small text. In fact, I was using them to get my page in the top results for some queries. Yippie..... I was to some extent able to drive traffic but that didn't last long( :-( ) as I had links from few sites that had a higher page rank.
And after figuring it out that methods such as keyword stuffing, hidden text won't work, I have removed them. As far as my understanding, the only way to be in the top results is to be popular(indicating a high page rank), have a lot of back links, also have outlinks(not to spam) and relevant content.

Of late, I have also heard of another spamming technique: Page Cloaking, Code Swapping. A spamming technique where one page is submitted to the search engine and another page is shown to the end user. Finally there is a difference in the content that is retrieved as search result and the content that is seen by the user.
Spam of such kind is combated by few search engines by revisiting the pages that are indexed regularly. Spammers may have a tough time here as they don't know when the crawler/spider would again show up.
But, if the user is identified as a search engine, a separate script can run and submit different content to the spider and fool it.

IP deliver is a variation of cloaking where the content is served based on the user's IP address.

Search engines have grown intelligent enough to overcome this spamming to an extent using few anti-spam techniques. I have heard that Bing, the new search engine from Microsoft, is trying to simulate users using bots to check if the content retrieved by the search engine and the user bot is similar.
Good idea, but this would almost eat up a lot of bandwidth. But, given the huge amount of spam on the internet, it is a worth for giving relevant/no spam results.