This is a fix for the 'Unable to load InstantMessage.template' error. This error only occurs when running SMFShop under SMF 1.1 (it doesn't occur under SMF 1.0, I don't think). If you're getting a similar error message in your error log, here's how to fix it:
Open Sources/shop/Shop.phpFind: (line 25 in an unedited Shop.php file)
loadLanguage("InstantMessage");
Replace with:
if (loadLanguage('PersonalMessage', '', false) === false)
loadLanguage('InstantMessage', '', false);