I made a little application that will download the new league of legend summoners rift map parts as an image.
Then put all the parts together again to form a full resolution version.
Here is the application: DownMap
If you need the full map you can just run option 3.
May take a while on a slow connection the parts are over 100mb total.
UPDATED: now the summoners rift map can be downloaded at different resolution, you will get an option for res 1-6