vim-bracketed-paste enables transparent pasting into vim. (i.e. no more :set paste!)
I recommend using pathogen. Once you have installed pathogen:
cd ~/.vim/bundle
git clone https://github.com/ConradIrwin/vim-bracketed-pasteOtherwise just copy-paste everything from plugin/bracketed-paste.vim into your ~/.vimrc.
You need to be using a modern xterm-compatible terminal emulator that supports bracketed paste mode. xterm, urxvt, iTerm2, gnome-terminal (and other terminals using libvte), Putty (for Windows) are known to work.
Then whenever you are in the insert mode and paste into your terminal emulator using command+v, shift+insert, ctrl+shift+v or middle-click, vim will automatically :set paste for you.
The code for this plugin was taken from Chis Page's answer to a StackOverflow question, I just packaged it.