Los sitelinks son creados por el robot de google automaticamente y lo hace cuando hay contenido que el considera relevante.
Según google mismo lo describe en su herramienta para Webmasters (
www.google.com/webmaster):
Cita: Google has not generated any sitelinks for your site. Sitelinks are completely automated, and we show them only if we think they'll be useful to the user. If your site's structure doesn't allow our algorithms to find good sitelinks, or we don't think that the sitelinks are relevant to the user's query, we won't show them. However, we are always working to improve how we find and display sitelinks.
Otro link interesante
http://www.google.com/support/forum/...79a13939&hl=es