I have a couple of things jotted down here I thought I'd put into a useful thread as I came across them.

Markable Objects: Those objects you find in various locations that you right-click on and Mark. "Arremis was here." I don't know if this has been addressed yet.

Water Objects: We've discussed this before, but I thought I would note that as I was running around in the Queen's Colony on Live, I was harvesting some nodes in the lake by the treehouse, and noticed that as I was only waist deep in water, as I moved, my Swimming skill kept going up. It seems that the client knows the difference from when a character is on land to when they pass into the perimeter of a water object, and obviously knows when the character is completely within the dimensions of the water object. I'm assuming educatedly guessing that these water objects have to be seperate for rendering reflections. I just happen to be watching the waterfall, and thought to myself at how well the rendering in game has been designed, and was quite impressed for the moment.