If you are placing a keyword in Meta Description thinking that it will improve your rank and than you are wrong. Just put any phrase in the description tag and search that phrase in the four search engines MSN, Google, Yahoo! and Ask. Yahoo! is the only search engine that will show a listing while the other three search engines do not see the description tag in order to match or rank a page.
These are the finding of a test posted at Small Business SEM. The tester, Matt McGee says:
I put a silly 3-word phrase in the “meta name=description” tag of one of my blog posts. In searching for that phrase on the four main engines, the search comes up empty in Google, MSN, and Ask. It gets returned in Yahoo. The post is indexed by all four engines.
But this does not mean that Meta Description has no use. It is important to get words that one wants to be displayed in the snippet.