Is promiscuous mode bad?

[aaron at daltons.ca (Aaron Dalton)]

I was running security/rkhunter and it warns me about my network card being in 
promiscuous mode.  I have a few questions:
1) What exactly is promiscuous mode? (I've done some googling but haven't 
found anything really clear)
2) Why might it be considered a bad thing?
3) How do I disable it if it really is bad?
4) What are the effects of disabling it?

Thank you *so much* for your time!
-- 
Aaron Dalton
http://aaron.daltons.ca