For me I guess it kind of depends on each individual. I don't have the confidence...or the legs...to pull it off and I'm only 25 but I've never really felt comfortable in mini skirts. The one you like doesn't look too terribly short and I bet you'd be super cute in it!
I think 30 is fine for a mini skirt as long as it's done in a casual way (no heels).
I'm 29 and I wear denim minis all the time during the summer. I own two (dark blue COH and white Miss Sixty) and am planning on buying one more this year (medium blue TR, a little longer) I usually pair them with flip flops or flat leather sandals for picnics, concerts, etc. But I have also gone out at night with a blousy top and heels & I don't think it looked tarty. As long as you can pull it off, I say do it :)
__________________
http://v247.tumblr.com One cannot perceive beauty, but with a serene mind -Thoreau
I'm 29 and would only wear mini's to the beach, but that's just me and my comfort level. I wouldn't think anything of a fit, young-looking 30-something wearing one.