I've tried the resume operation on wput, but it always ended up to corrupted files with larger sizes than the originals. (I've made many tests with different kinds of files and sizes).
I'm running wput 0.6.1 on fedora 14 (x64).
I attach a zip file containing an original file and the same file after a resumed upload with wput.
If you want to test my ftp server, feel free to ask me: I will send you an account and password by email.