Although not related to Stealth, Jorb confirmed somewhere that crawling past animals is more efficient, I'm just too lazy to go look for it now. (It was on a update thread though, if I'm not mistaken... maybe the one that added bats.)
Also, Stealth improves Mirkwood Offering quality... Not really relevant but interesting when you haven thousands of experience sitting there...
I'd like to see Stealth influencing more stuff, though... Like improving your ability to evade animals and maybe create some sort of 'Hiding' skill (where you disappear if standing still) like Ultima Online has/had. Just standing still, though...
hidden movement (as in UO's Stealth) would be ridiculously abusive.
---------------
EDIT:
I said I was lazy but I don't like being lazy, so I did my homework:
jorb wrote:They are significantly less likely to attack if you walk slowly past them.
Source