Tara Calishain has noticed that Google has raised the number of words allowed in a query from 10 to 32, without mentioning it on the help pages.

This news may have no effect for the standard user but this new limit allows developers to create better tools based on Google queries. You can also add more negative terms to restrict your query.

gives some details about the implementation:

The support for the new limit is somewhat patchy :-

• the 32 word limit is used on the main search engine, image search, Froogle, and via the Google search API
• the 10 word limit is still in force for Google groups, news

Philipp Lenssen gives a list of usages of large queries:

• When you automate search tasks using the Google API, you often find yourself hitting the 10-word limit.
• When you search for quotes from a text, you would hit the 10-word limit very fast.
• When you want to exclude a lot of words from a search because your result is not specific enough.
• Meta search engines (or an "uber" engine like FindForward) may take a user's query and add their own "tuned" words in the background. This means when the tuning uses up 6 words, and the user entered 5 words, 1 tuned word was ignored.
• When you wanted to trace all synonyms Google knows for a word.