Small business owners tend to be shrewd and place the interests of their company above all else (unlike corporate middle managers who might place their own career progression higher). This being the case, vendors may have a tough time convincing them of cloud, and getting them to accept the loss of control, ownership and security of their data. Having control and ownership is pretty much what drives entrepreneurs.
One obvious solution is for the SMB owner to buy some cheap storage from QNAS or whoever and stick Owncloud in it. QNAS could sell them a ready-integrated Owncloud. I'd buy that for a dollar.