I think plogger does this. You need first to set it up and then tell blogger through the backend admin interface that you are going to import stuff. First of course, before you do this, you have to create at least one collection and one album.
You could use cordoval's approach (adding all of your folders / files to the uploads/ directory and then importing them from the Admin -> Import tab). Please be aware that Plogger currently only allows a setup that is 2 levels deep: Collection/Album. If you have more or less sub-directories than that, Plogger will not allow it. We are working on updating this, but it will be in a future release sometime.