That depends on your definition of "worth it" is, obviously. I have a rather large JS file in a project:
- Original state: 41.7 kB
- Minimized with YUI compressor: 27.8 kB (~67% of non-minimized)
- Non-minimized, gzipped (with 7-zip/"normal" compression level): 10.8 kB (~26% of original)
- Minimized and gzipped: 7.45 kB (~18% of original, ~69% of gzipped/non-minimized)
YMVV, but as we see, the relative size of a minimized to a non-minimized file is about the same even after gzipping (approximately two thirds). I balanced those 3 kBs I'd gain by minimizing against the weight of the rest of the page (== considerable), and decided against bothering with minimization.
Minimization does give your developers an advantage, though - as it strips out comments, you sprinkle the code with bug notices, explanations for kludges or complaints about stupid customers, lusers, management, etc, without risking embarrassment if someone does a View Source.