Short answer:

SCJP is worthless as a credential. SCJD is worth something, but IMHO would
only merit "experience equivalent to about two years in the industry" if
there were no other experience on the resume. The other Java certifications
I don't have experience with.

There is a chicken-and-the-egg problem with the certifications; so few
people have them that nobody bothers asking for them. Because nobody asks
for them, no-one bothers to obtain them. Knowledge of the Java platform and
language is generally proved during a technical interview in other ways.

-- Adam Maass

I generally pay attention to it when hiring.  It won't get you a senior-
level position, though.  Depends on what your goals are.

It depends what you define as useful. Maybe useful for learning but not
so useful for getting a job.

I found the Sun Certified Web Developer exam a good introduction to the
JSPs and Servlets and it helped get me a job using that technology.
However I found the SCJP tends to focus on the less useful and more
cyptic parts of the language (inner classes etc).

The value of certification really depends on the employer though.
Experience will always be more valuable, although some employers will
pay attention to any certification. However if you are having trouble
getting the experience then it is better than nothing.

Study for the SCJP will expose you to many aspects of the language
you might otherwise skip and give you more confidence.

Bill

If an employer has to choose between two candidates of approximatley
the same ability, the Programmer Certification exam can tip the
balance. I have some information on the exam which you can see at

http://www.examulator.com/moodle/course/view.php?id=3