Hi,
Thanks for your comments and votes on this idea. I'm pleased to advise that in version 7.0 we introduced a Setup Wizard which allows users to easily upload a logo image for display in the public/client areas, emails, the printable and PDF invoices.
The setup wizard is displayed upon first login on a new installation, and can be accessed at any time via Help > Setup Wizard if you would like to change the logo at a later date.