On December 26th, Matt Cutts tweeted that "Google will be looking more at Cloaking in the first quarter of 2011."
Cloaking, as defined by Google refers to the "practice of presenting different content or URLs to users and search engines. Serving up different results based on user agent may cause your site to be perceived as deceptive and removed from the Google index." Cloaking is against Google's webmaster guidelines.
Matt's tweeted, "Google will more at cloaking in Q1 2011. Not just page content matters; avoid different headers/redirects to Googlebot instead of users."
[tags]cloaking,url cloaking,search index,googlebot,google index[/tags]