Heard it from Google web spam Engineer Matt Cutts,

“Google does not use the keywords meta tag in our web search. To this day, you still see courts mistakenly believe that meta tags occupy a pivotal role in search rankings. We wanted to debunk that misconception, at least as it regards to Google. Google uses over two hundred signals in our web search rankings, but the keywords meta tag is not currently one of them, and I don’t believe it will be.” Matt says.

Here’s the video for clarifications…

Google webmaster blog also officialy confirmed the said search algorithm changes.

So forget spamming your target keywords in your site keywords meta tag because you’re just wasting time, I suggest that you better focused on content and brand building.