To add some personal thought to this node:
I once worked for a small organisation who were contracted by Sun Professional Services to provide system administration personnel to other organisations. This organisation was unusual in that the total number of clueless sysadmin-wannabes they employed was zero. It was (and presumably still is) a company comprised of very, very smart people.
For some reason, they thought it might be a good idea to get those involved in system administration Sun Certified. This makes sense from a management point of view - "qualified" personnel are much easier to market to potential clients. I guess you could also say that it would help justify the hefty fee we charged Sun for our services, too.
The problem with this type of "course" is simply that you can't just answer 100 multiple-choice questions and instantly become a good system administrator.
A good sysadmin requires the ability to reason a certain way and to think laterally. I can't think how this can be quantified easily with a test. Certainly someone who scores highly in the test needs to know quite a bit about Solaris. This is basic required knowledge for any sysadmin.
What I can't see is how Sun can claim you to be "Sun certified" - implying that you're a great sysadmin - if you can explain the command line arguments to add a printer but can't necessarily work out why print jobs take forever to spool and print.
Quite a lot of the questions you may get on the test may relate to aspects of Solaris you'll never need to deal with in your day-to-day work. If you don't know how to set up PPP though, you may well fail the exam. Again, I don't see how this makes much sense unless you perhaps run an ISP.
I wouldn't say that this certification is worthless, but any sysadmin worth his salt should be able to ace the test without studying.
Much more valuable than knowing all the answers is the ability to find out the answer when you need it.
You don't need to know everything about Solaris to be a good Sun system administrator.
If you want to try your hand at a simulated exam, point your browser at