Apparently this shipping is canon. these two have been friends even before Twilight came into their lives.
Nice vector of the two.
Fluttershy seems to have a closer bond with Rarity than with any of the others, and I think it's cute.
It was implied in season one that they already long-time friends before the series began, when Rarity mentioned their weekly spa get-togethers.
At least it's not Fluttershy and Pinkie Pie. You guys know what I'm talking about. XD