The MobileSafari Download Plugin has been ported by jonmisurda from iPodTouchFans. This plugins that allows you to download things throug the iPhones and iPod Touchs Safari.
It support zips, rars, dmgs, etc, exes, .torrents (but is not a bittorrent client), and all media files that are playable with the MobilePlayer on the device. Also for media things, you can choose whether to downoad or stream by click play in mediaplayer button.
To install it, unzip this file and copy the File Download Plugin.webplugin/ folder to /System/Library/Internet Plug-Ins/ and reboot your iPod Touch or iPhone.
I have installed it and it works flawlessly.