Pitivi uses stock icons but doesn't use the stock labels that come with them, notably "Quit Pitivi" and "About Pitivi".  Ideally you want to let the labels that come with the stock items show through, this way the translations will show through and you save your translators from unnecessary work.  

Aside from that I would recommend you carefully abstract the use of APPNAME anywhere it occurs in your program.  No one ever knows in advance if they will need to change the name later.  (Being able to change the name and branding might be an opportunity to provide a supported commerical version like Staroffice/OpenOffice does.)