I just ran into this new app and have been testing it for two days now. It is called Airdroid and is free at the Market:
No need for cable, only wifi connection and it works great. Even let me back up system files, SD card files/apps and some other things. Great "NonNandroid" back up for not rooted phones and its pretty fast. All you need is the app and a web browser and you can import/export/delete etc. This is first app for this that works fantastic. I'm giving it a 5 star since it works with both PC and Mac and is pretty fast. Just thought I'd let others know since its a new app.
Everyone once in awhile my web browser will force close on my Mac but not that often. If you have trouble with getting your computer to see your phone on the PC or Mac definitely give this one a shot. It has never failed to show up on my computer and the app itself has never force closed, it was my browser on my Mac. I might test it out on Firefox or another browser instead of Safari and see if it works even better. If you don't like it and you don't feel its worth it, I will double your money back! Yes! That's right I will give you double "Free" no questions asked!
P.S. I just noticed if you hit the menu button when you open the app it has "Tether and HotSpot Mode". I haven't played with that yet to see if it does anything. I'm also feeling kind of lonely, would someone who finds this app a 5 star rating give me a "Thanks". I only have two and 3 times the charm. hehe