This is a great plugin, but I can't get it to work. For the record, I am using WordPress 3.0 on a multisite.
When I upload an image, the image size is 0 pointing to an error when it tries to convert the image. PHP logs give the following error:
PHP Warning: rename() expects parameter 1 to be string, object given in [snip]/plugins/imsanity/imsanity.php on line 58
Hoping for a resolution!