If I create a server with a texture pack greater than about 12MB (don't know the exact size) it would download correctly. It creates a zip file in the mp-cache folder, but that file has a size of 0 kilobyte. After that the game thinks that the textures are loaded.
As a lot of Mods enable additional textures or higher resolution this gets pretty annoying if you have for example a creative server with a custom texturepack and need to tell users to manually download and install it, so basicly as in older Minecraft versions.