In many PvP oriented MMORPGs sieges are a key feature. They are even more important in a sandbox MMORPG like ArcheAge, in which player-built structures and cities can be attacked and defended.
That’s why it’s not surprising to see XL Games putting a lot of development effort to hone the siege mechanics as best as possible. Today they released a new trailer of the 4th phase of the closed beta, showing how far they have come. That’s quite far, as it looks spectacular (and very chaotic).
You can see by yourself by checking the video after the cut.