Official Google answer: When did "Did you mean" search results begin to be displayed?

Question:

When did "Did you mean" search results begin to be displayed? And what is the criteria for presenting "Did you mean" search results above the normal results?

Google's Matt Cutts answers:

Summary of the answer:

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Question	Views
How does Google rank sites which run on a different port than the standard port 80?	898
When I do a Google search for my business name, Google suggests "did you mean:" with some other company name. Is there anything we can do to keep that from happening?	674
If you have a lot of blog content for a new section of a site (100+ pages), is it best to release it over a period of time, or is it fine to just unleash 100 pages?	905
How accurate is Google's backlink-check (link:...)?	1,107
If you have inbound links from reputable sites but those sites do not show up in a link:webname.com search, does this mean you are not getting any 'credit' in Google's eyes for having inbound links?	180
Is Google aggregating SearchWiki data with Analytics for ranking?	704
How will Google search work with dynamic HTML pages (and I don't mean JSP or other Web 1.0 technologies), like applications that are built with GWT?	812
When you search for something, let's say "LinkedIn", you will notice there are some quick links on the search result such as "Jobs, About, Advanced" etc. How does that work?	830
As Google's algo evolves, is it better to have exceptional links and mediocre content, or exceptional content and mediocre links?	1,018
Is it a good thing to put 'nofollow' in links to a disclaimer, privacy statement and other pages like that with the internal PageRank in mind?	928

Question

Views

How does Google rank sites which run on a different port than the standard port 80?

898

When I do a Google search for my business name, Google suggests "did you mean:" with some other company name. Is there anything we can do to keep that from happening?

674

If you have a lot of blog content for a new section of a site (100+ pages), is it best to release it over a period of time, or is it fine to just unleash 100 pages?

905

How accurate is Google's backlink-check (link:...)?

1,107

If you have inbound links from reputable sites but those sites do not show up in a link:webname.com search, does this mean you are not getting any 'credit' in Google's eyes for having inbound links?

180