So, you are looking for a way to upload files to an FTP site using MSBuild tool.
Me and my colleague Lev try to do exactly that, we search and found msbuildtasks.tigris.org which should work, but didn't. We also found MSBuild Extension Pack which worked, but lack the proper abilities of upload whole directory and not file-by-file.
After some more search we found one tool that worked - NcFTP
This is a solid long-live FTP client application with command line interface.
It's free, it's simple and it's does all we need from FTP client.
So, if you also looking for way to upload file to FTP using MSBuild simply use Exec with NcFTP.