I'm the Misa. I make the pack of textures.
I've been a a part of the Minecraft community since around mid 2009, and have been making custom texture packs since around then for creative, indev, infdev, alpha and beta. Wasn't until November of 2010 that I had my first public release as Misa's 64x64 Realistic Overhaul. (The first 64x64 texture pack ever publically released to my knowledge, also the first to have edited and included every single bit of editable art in the game.)
The texture pack started off as a 16x16 terrain.png for Creative mode back nin 2009. I made it for myself and had no intentions of ever releasing nit. As time passed, Indev came along and I adapted this terrain.png to nbe used with it. It wasn't long after that that Infdev came around and In found out you could get by with 32x32 sized tiles, so I reworked my oldn tiles, maintaining the general look and feel of my original pack, half nof the source files I made were in 64x64. By the time Infdev became nknown as the main Survival mode, MCPatcher had caught my eye. Since manyn of my source files were already in 64x64, updating the rest to that nseemed the next logical step. At some point though I began to reach a ncreative block and was unable to objectively review and improve my own nwork. To solve this I decided to upload and share it to receive nconstructive criticism. But before I could do that, I decided that a nterrain.png wasn't enough for a release of a texture pack for me. And nreleasing a WIP was out of the question, so around the time of the nHalloween update, I spent a whole day doing nearly every single other npiece of art I could edit,including the mobs and items. Uploaded it and ngot the criticism I needed to improve my pack even further for my own npersonal use. ...Or so I thought! :P