In versions prior to 2009 if one needed a new material one needed only enter it ONCE, and it would stay there so they would be not need to continue to add it in because it isn't wiped out when one exits the pipe, parts list dialog.
For clarity, it appears that 2010 if one is logged on as Administrator the changes stay, and in 2009, if one adds a unique material it will not stay attached to the pipe; even when the program is run as admin.
Editing the XML seems to be the ONLY way the new material will stick ,<R2009>.
Somewhere along the way , r2009 they 'fixed' is such that the user MUST add the material in the XML file, probably because they couldn't get the stupid column to stop truncating the entries, so they simply force the user to now edit the XML file.
NOTE: this post is corrected after testing with 2009, 2010 further tests will be done with 2008 upon my return to AZ next week.