I've never seen anything official given as a preferred mark-up approach. Have you considered using View Source to see how sites with breadcrumbs showing in the SERPs are doing it?
SanDiegoFreelance
8:14 pm on May 8, 2011 (gmt 0)
I believe this would be the most "official" information [google.com...]
There is also a video for "why breadcrumbs are not showing" from Googlewebmasterhelp
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.
dombili
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!
indyank
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 >
tedster
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"