Just a heads up if you are running the install (for mod devs) and get something along the lines; 
  
 
error: error reading C:\forge\mcp\lib\asm-all-4.0-source.jar; error in opening zip file
error: error reading C:\forge\mcp\lib\guava-12.0.1-sources.jar; error in opening zip file
 
  
This seems to be caused by the fact that the downloaded jars weren't downloaded successfully - almost certainly due to the file download site being down. 
  
Anyhow, just thought it might be useful ...