The makers of iPhoneBrowser have updated their tool so it will work with 2.x.x iPhones, from Windows computers that have iTunes 8 installed (apparently it has to be compatible with that). This is the first version published since January.

iPhoneBrowser is a great tool if you don't want to (or can't) create an SSH connection to your iPhone. You can access all the files, without the annoying warning that DiskAid gives when you access the root filesystem. iPhoneBrowser also has the great advantage that you can preview pictures (even the "special" iPhone .png files), sounds, and text files, and in the menus it has shortcuts to a number of important locations (WinterBoard themes, Preferences, etc, and anything you want to bookmark). It is open-source and free.

Disadvantages: it's slower than SSH, it's still in beta (sometimes crashes), and like other non-SSH-programs it can't edit ownership and permissions of files (so ultimately you can't install applications with just this).

Download link: http://code.google.com/p/iphonebrowser/downloads/list