<p>I would like to write an application that will copy MP3 files to a SanDisk Sansa M240.  The SanDisk doesn't have a drive letter and uses MTP for file transfer. 
I stumbled through the sample of connecting to the device at : <a href="http://blogs.msdn.com/dimeby8/archive/2006/09/27/774259.aspx" rel="nofollow noreferrer">http://blogs.msdn.com/dimeby8/archive/2006/09/27/774259.aspx</a></p>

<p>but once connected, I can't figure out how to actually copy files / create folders on the device.</p>

<p>I am very surprised that there aren't any .Net wrappers for this COM library.</p>

It looks like dimeby8 posted some code that handles data transfers.  Check other posts in his blog, especially:
Sending MTP commands through WPD part 1
Sending MTP commands through WPD part 2
Sending MTP commands through WPD part 3