I'm assuming you are probably more interested than most in things that affected Siege, so here goes:
Stygian Abyss expansion. (Huge. You need to catch up on this if you left before it happened.)
High Seas booster.
Leveling of Magincia and player housing in Magincia (ho hum on most shards, big deal on Siege)
All accounts can have 2nd house on Siege or Mugen, or house on prodo shard if already have house on Siege or Mugen.
Lots of armor changes and weapon special move changes last year.
Faction artifacts rendered impractical for most and devs are promising a replacement ("Virtue vs. Vice")...soon?...for factions.
Also see this thread from last week started by someone else who's been gone about as long as you have:
http://stratics.com/community/threads/so-whats-up-with-uo.309535/.
I think that's under 500 words but I didn't count.
So are you seriously contemplating coming back or are you just teasing us? LOL