Yes.  How well it works depends on the individual ball.  I have seen everything from nearly a complete revival to almost no noticeable difference.  Generally if a ball is saturated and just feels "slimy," then I think its a good idea.  I have rejuvenated a ragin inferno 6 times and counting for a teammate and never had any issues.  The temperatures don't get hot enough to really effect the grips... although you may want to think about having them replaced if they are the originals and you are getting the ball rejuvenated (suggested every 60 games?).  Rejuvenations seem to work best when done in combination with a resurfacing.

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Joe Theismann's MNF idiot quote of the week (regarding Grossman):
"His teammates want him to do well."

i have had great luck with the use of the rejuvenator on my brunswick equipment for the past 3-4 years. cleaning your ball(s) every time you use them goes a long way to slowing down the absorbtion of oil. if you neglect your ball(s) and then expect the rejuvenator to perform a miracle after 500 games you need to look somewhere else for help. i agree that using the rejuvenator in conjunction with having the ball resurfaced with a haus-type machine will produce the best results.