Google Crawler is a Software Application that "obey" to Metatags Robots or Robots.txt to visit the website after a month, a couple of days, or in the case of big web sites like Hubpages, = a couple Hours.
This means that your content Headers, Title, Keywords will be updated fast.
Be careful when changing the Title, do not take off some good words, replacing to random ones, because will crash your ranking inside search engines data bases
Want to learn more? Take a look in this article i made ( http://hubpages.com/technology/programming-a-baby-... )