Graphical updates in Blockland is an interesting subject. Mainly because Badspot rarely mentions any kind of graphical improvement. The only thing he really does mention is how it will affect performance, not "We can do this, but not that."
I am sure effects like mirrors are brick shadows are possible, just not really something worth taking time to do. The only shadows that are really decent in blockland are interior shadows, which cast upon themselves unlike most shadows.
Sure you could give Blockland 8x AA, Bloom, Bump Mapping and Displacement Mapping, but would it honestly be worth it? Except for taking pictures, it would look stupid and get in the way. Walking around with lights shining everywhere with a really detailed player model and shadows wouldn't fit in at all. Blockland's graphics style is meant to be simple. Besides pictures, the only reason I see people wanting it is so they can say Blockland has it.