Winston Burton wrote an interesting article on Search Engine Land that dealt with the importance of keywords and ranking in Google. One of the key points made was that the answer varies based on your domain name.
From the article:
Do you even need keywords on the page to rank anymore?
The answer will vary depending upon your domain. If you’re a high-authority site that has high-quality inbound links and useful content that is relevant for a given keyword, you may find yourself ranking well for keywords even if you did not specifically include them on your page.
When you don’t have the exact keywords on the page but are still relevant enough for a search term that you come up in search results for it, this is called query expansion. For example, perhaps you have a webpage about cycling that ranks for “biking,” even though you use the term “cycling” throughout the page. Google is becoming smart enough to understand that these terms are synonymous.
The point? Even if you are tracking keyword rankings, you may not be getting the full picture; you could be ranking for terms you don’t know about because you didn’t think to track them in the first place.
Read the full article here