It would be real sweet if you created the ability to use the same FTP login information across all blogs or certain ones. I guess the optimum would be to have the ability to create ftp accounts on their own menu... So perhaps if I have blogs in the niches:
cars, poker, vacations...
... I could set up accounts on different servers or the same server with the images residing in directories named after the niche.
Then on the blog settings would be a drop down menu populated by the accounts I have created. Now when I set up a new blog I just select FTP for images and then select the niche it is in... done!