Typically H1 tags are reserved for page headings, i.e. on a blog post the blog post title is very often the pages H1, or top-level heading as the W3C puts it.
On the SEOmoz home page they currently have "SEO Software." as their H1 tag, which seems perfectly reasonable and to me fits the W3C criteria.
However, what if the primary keyword for SEOmoz was "seo community" so they decided to wrap just those two words in the sentence that follows on their home page and maintain the existing style of the words "seo community" with CSS. (see attachment)
Are there any arguments against doing that?
Would Google be able to detect this? If so, would Google care?
I do believe the overall importance of the H1 tag has lessened to a degree, however I still believe they are valuable to an extent and would love to hear anyone's thoughts.