During my recent visit to WDW it was also the 30th birthday of Horizons. Horizons first opened in EPCOT on October 1, 1983. I was hoping that there would be some super special Limited Time Magic event for this important anniversary but when I asked about it at the gate, the young person didn't know what I was talking about. That hurt.
Disney did do a nice tribute in the form of some D23 posts titled Reaching for New Horizons. Content is for members only and worth the read. (Remember, you can join for free!) These were written by Michael Crawford from Progress City USA who also has a great summary with some awesome images summarized in a post titled Reach for Lost Horizons.
The Horizons fan base came out with a lot of good stuff to celebrate!