(spoilers)
Even though this is the first time we've heard the official names of all of Pie family in the show itself, those names were actually first mentioned in one of the books that came out some time ago. I've never bothered getting any of those books, but I have heard from people who do have them about certain little bits of interesting information (such as Princess Cadance was born as a pegasus and later on ascended to an alicorn, kinda like Twilight).
Anyway, it was nice to finally have some canon characterization for the rest of the Pie family besides Maud (who we already know very well). The parents, Igneous Rock (father) and Cloudy Quartz (mother) speak in ye olde style. Limestone Pie (the purple sister) is the grouchy manager of the rock farm. And Marble Pie (the dark grey sister) is very shy and never says anything besides "Mmhmm." In fact, this is the very first time we've ever seen the latter two as they are in present day, so we now have not only their cutie marks but also their adult hairstyles.
For this episode, it was very interesting to have not just two characters but two entire families interacting with each other, showing the huge contrasting backgrounds that the two main characters, Applejack and Pinkie Pie, come from. Also, the intro showing how Twilight and Spike developed their own holiday tradition served as a nice little hint of what happens later on in the episode between the Apples and the Pies.
Well, next week's new episode is the one that was leaked a while ago, but I've done well to avoid watching it, and I will continue to avoid watching it until after it's intended airtime next Saturday.
(end spoilers)