Ask HN: Programmatic Googling to Recreate xkcd results

I am trying to access Google search results programmatically.

For example, let's say I wanted to recreate xkcd's X Girls Y Cup results.

http://xkcd.com/467/

AFAIK, Randall entered these results manually "X Girls Y Cup" into Google search.

Is there any way to do this programmatically? Does Google have an API that I can use to return the number of search results for a given search string? Is there any way to hack it by abusing the Google URI?

Any ideas for how to access Google's search results would be really helpful.

Thanks!