One of my sites has a bounce rate of 16.79% over the last month, but is receiving most of its traffic from clickthrus from another of my sites that gets its traffic via
SEO and has a bounce rate of 55.37%.
SEO traffic generally has a higher bounce rate then PPC (or other targeted traffic). With PPC you could look at which keywords have a poor bounce rate and either delete them, or send users to pages with content more targeted towards these keywords (or use the referrer info to dynamically change bits of the page according to the keyword used).
With
SEO looking at the overall bounce rate isn't particularly helpful as you have less control over the longtail keywords, which may be skewing the headline figure. You need to drill down to really be able to draw any meaningful conclusions.