growing in the goo

I've noticed the term "navel-gazing" popping up more and more, but I'm not quite exactly sure what it means. But I do suspect that I'm guilty of it, haha.

So, a few definitions:

from dictionary.com
na·vel-gaz·ing /ˈneɪvəlˌgeɪzɪŋ/ Pronunciation Key - Show Spelled Pronunciation –noun Slang. excessive absorption in self-analysis or focus on a single issue.

from merriam-webster (online)
navel–gaz·ing noun : useless or excessive self-contemplation

Well, that about exhausts my list of reputable online dictionary sources. But I wonder - what's the difference between introspection and navel-gazing? Is it introspection when you think about an issue, but navel-gazing when you can't stop talking about it and don't let it go?

(and yes, I'm aware that I'm flirting with the line of navel-gazing about "navel-gazing" right now...)