There is a new version for both Mac and Windows. I always loved it because you can get into the file system of the iPhone without the extra steps of OpenSSH. I used to use this with my 3G all the time but then when I got the iPhone 4 it still worked but not as fluid. I could only do one thing and I would have to shut down the app because it wouldn't refresh. I haven't tried the new version with the iPhone 4 yet but I tried it on iOS 4.3.3 and it worked great I'll test it with my iPhone 4 tomorrow and update. This is just extra info for the people who don't want to do the extra steps of SSH.
Mods please move this to the JB forums sorry for my mistake