Running PD9 and it is awesome! I have Dropbox an Skydrive installed on my Mac, but on my VM I just see iCloud. All boxes are checked on VM configuration. Maybe this happens because I have two drives on my Mac: main drive is one SSD with my OS 10.8.4 and apps and and the other is one HDD with my home folder and all other data. Could this be the problem?
In the configuration, you have two sections, the top one deals with what is shared from OS X on Windows and the bottom one with what is shared from Windows on OS X. Currently, you can only share your iCloud, Dropbox our Google Drive from OS X on Windows. And from Windows, your Skydrive. What this means, in case it isn't yet obvious, is that Skydrive installed on the Mac isn't shared with Windows, only Skydrive on Windows is shared with the Mac.
I have the same problem. I do not see my Dropbox on Windows 8 in Parallels. iCloud and Google Drive are there, but no Dropbox. This is an essential new feature for me to upgrade to Parallels Desktop 9. For your information, my local Dropbox folder is not in the default location (Home), but on my second Hard disk. Maybe this is a problem?
My dropbox is on a USB drive on my Mac. I want to use the same one in my windows VM, but when I try to mount it, it says it is a network drive and refuses. So how do I get the VM to use my Mac dropbox folder? I tried to mount psf:dropbox.
You might share custom folder with your VM (Options - Sharing - Share Folders, Custom Folders...). Point it to your Dropbox folder on the USB drive. This way it is shared with your VM. However this should be done automatically with the new PD 9.