In today's times, where the Job Market it very tough for Java programmers, there are some important aspects to this.
First of all, I think that as many keywords you can get on your resume (the most marketable ones current), the better. Even if you only know a little. The reason? Because the resumes are put into a database and logged and searched by HR people (including recruiters), who only know them as buzzwords. These are things that can get your resume noticed and hopefully get you in the door for an interview. I even leave a lot of my very old skills (like Fortran, and other vertical market skills) in case somebody does a search for these technologies when looking to redesign a legacy system.
Now once you get in the interview, you better be honest about how much you know about everything, because you say you know something like
EJB, Design
Patterns, you will get grilled by the tech interview. If I'm not particularly strong in a skill but have some experience, I explain how I was involved in it. What I mostly push is proof through my job experience that I can pick up a new technology quicky and run with it.
Some companies may need a particular skill right away and don't have the time, or resources to have someone develop it.
For example I had a 2 1/2 hour interview (where I was really grilled on my knowledge and experience). They really wanted someone that had direct experience with MQSeries, MQSI (and message oreinted middleware. I had only worked on projects where integration of an in-house messaging system that used MQS under the hood. They picked another candidate that had that specific experience. But I was called up a week later because they opened up a new position and thought I would be a good match to fill it.
MQSeries was prominent enough on my resume to get me in the door, and it indirectly led to a job.
Please keep this in mind when looking for a job. A good company will appreciate your skills and your aptitude to learn more than a specific nitch.
The interesting thing is that my 1st assignment has been to develop a process based on RUP, which is something that I don't have as much experience on, but I'm learning much about along the way.
So my advice is to use everything you have to get your foot in the door, and be honest at the interview (so you don't get in over your head).
[ March 04, 2002: Message edited by: John M Brown ]