As SanDiegoFreelance says, you can either use Microdata or RDFa to do it.
Google do say that they can now automatically detect breadcrumb navigation (not marked up in RDFa or microdata) - and this might be true - but one of my sites does breadcrumb navigation like you mentioned in your OP and Google have never detected it. Then on a new website I marked it up with microdata and Google shown the changes in the SERPs within a week.
4:39 pm on May 9, 2011 (gmt 0)
@tedster: I got what I posted from a site that was showing up already. Just wanted to see if there was something more structured.
@SanDiegoFreelance: Thanks a lot, exactly what I was looking for!
4:49 pm on May 9, 2011 (gmt 0)
I think > is good enough for google to detect the breadcrumbs.That worked for me.
But I have also seen some major sites, who deliberately seem to be avoiding the breadcrumbs by using an image instead of >
5:20 pm on May 9, 2011 (gmt 0)
With regard to the character in use, on Google's Help page example, they are using › not > - that seems like an odd choice to me, because "greater than" makes at least some intuitive sense to me, compared to a "right single angle quote"