Ideally, depth is visualized as a complete path from the home page down through all levels of the information architecture, revealing all the higher-level structures inside of which the current page is nested. On a large site, a full list of all the levels can become overwhelming, so, as a compromise, the new Sun templates provide an abbreviated view of navigational depth, with three levels shown at the top of the page. If the current page is more than three levels deep, then intermediate levels are elided to simplify the display. Only if you are running a large and heterogeneous site. Sun's website has a large amount of highly diverse content which is why we need elaborate navigation support and a strongly stated unifying visual look of the navigation template.
Smaller sites can get away with a much simpler approach.
The figure shows the navigation area from Toby Braun Information Design . Also note how the use of standard link colors make it very clear to users what parts of the site they have already seen. Homogeneous sites can use simpler navigation that emphasizes one or two organizing principles for very large collections of pages. For example, news sites can use a time line to hide most older stories unless the user explicitly requests them. Also, by encoding richer attributes in XML, user-defined views can focus on pages of interest to individual users.