Hairy?

I adopted a stray kitten 3 weeks ago, she was found in a coworker's garden. My coworker couldn't keep her due to family allergies, so I found myself adopting her once my coworker bought her into work (what can I say, I'm a sucker). I now have 3 cats, 2 grownups and 1 baby. When Lily first moved in she was about a pound and roughly 3 weeks old. She's now officially 5-6 weeks old, according to the vet, who gave her a clean bill of health.
I know this is neither here nor there, but I was wondering what exactly the qualifications for medium-hair length is . . . I've got 2 domestic shorthairs (both rescues from the local SPCA), and Lily is definitely much softer and has longer fur than her big brother and sister . . .
-Ali

If she's only 5-6 weeks old and with longer hair than your others, she's probably a longhair - it can take a couple of years to get a full coat on a longhair cat, and at 5-6 weeks often the only difference between a longhair and a shorthair is 'a little fluffier'. Time will tell

I've had kittens that seemed to have longer hair as young babies (under 2 months old) and turned out to be shorthair (but dense). Others have looked shorthair and grew to more of a medium hair.

I'd just wait and see and decide when he/she is about 4-6 months old what they will be. Kitten coats can change as they get older.