Okay TECHNICALLY they're just hoofwarmers (no soles; I tried a tube-sock version but the decreases weren't flat enough for hooves). I was going to give them a scalloped edge, but they fit so perfectly and looked so cute that I decided to just leave them. Miss Rarity could make a paper bag look fashionable!
Truth time: I bought Rarity purely because I wanted to make socks for the Fashion Style Luna and couldn't wait for her to come out (still no release date, cry, please come out in time for my birthday). But she turned out to be totally fabulous by herself, and I'm glad I got her! There's just something really appealing to me about the G4 molds. I know a lot of people think they look odd, but I love them!
The hoofwarmers were deliciously easy and fast to knit up, especially once I said "aw, screw it" and just made them little tubes instead of proper stockings. Here is the pattern if anyone else wants to use it (or improve on it, I know I suck at knitting):
yarn - fingering weight
gauge - 4 sts per cm
Cast on 24 sts evenly to three dpns, work *k1,p1* rib for 4 rounds. Switch to stockingette and work for 11 rounds. Bind off loosely. Ta-da! (I free-handed the cutie mark symbol in duplicate stitch afterwards, so no pattern for that, sorry. Rarity's is easy to figure out though.)
If I figure out a nice flat decrease that works with hooves, I'll post it! Or maybe I'll just comb Rarity's mane some more. That sounds like a much better plan.