A welcome change! Hopefully it should help those that aren't too up to speed on Bitcoin realize that they don't have to buy an entire Bitcoin. ($1000+ will be quick to care most people off.) By switching to a mBTC format, hopefully more people will be willing to buy a few mBTC's.
(Also, got to love Bitcoinity's sense of humor. There've been some pretty funny gifs in the past when BTC reached certain highs.)