Search engine cloaking will get you a penalty…no question about it. In this video Matt Cutts goes into detail about what exactly cloaking is and how bad it is to use it. To learn more about cloaking visit the official Google cloaking page and you will know everything you need to know about this technical issue.
What is cloaking?
“Cloaking 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.
Some examples of cloaking include:
Serving a page of HTML text to search engines, while showing a page of images or Flash to users.
Serving different content to search engines than to users.
Provide alt text that describes images for visitors with screen readers or images turned off in their browsers.