Dropzone 0.6 has now been released and fixes the issues with the ImageShack and TwitPic destinations. You do not need to re-install these destinations, just updating Dropzone by right clicking on the dock icon and doing ‘Check for updates…’ will be sufficient.
One other note, if you use the Dropbox destination it has recently been updated. You can download the updated version here. Many thanks to Philipp Fehre for keeping this up to date.