Couse gnome-base/gnome-mount is depcrecated (Bug 349012) i deinstalled it. Now PCmanFM can't mount USB-drives any more. I tried to install sys-apps/pmount (Bug 349015) but that doesn't solve the problem. P.S: sorry for my bad english.
Works fine here, 0.9.7* with gnome-base/gvfs[-hal,udev,gdu] or 0.9.8* with udisks. Make sure hal is not in USE flags or installed.