Theres plenty of remote desktop apps that work with windows and mac to let you access your pc or mac harddrive, and yes, the shared folders as well. As far as peeking into the shared folders over the network without using remote desktop, I dont know, but a good alternative (which only requires a bit more work on the computer side) is to use dropbox. Pull the files you want to be shared into dropbox and install the app on your iOS devices...or if youre on the Lion betas and iOS5 betas, use icloud.
Come to think of it, if youre jailbroken, you can SSH into your home/network'd computer and access the shared folders that way. I would try it and get back to you but my ipad is on iOS5 unfortunately.