Ok, so it seems the link and image buttons (and a few others) have moved from the toolbar to a right click context menu in the latest version of SS. This is great for windows users, but a pain in the butt for Mac users....especially those who don't have new 2 button mice.....
How can I reinstate the buttons to the tinymce toolbar???
You can also completely customize the buttons in the editor, by using ->setButtonsForLine( <lineNr>, <buttonA>, <buttonB>, ...);. For more information, I suggest you have a look at the HtmlEditorConfig class (sapphire/forms/HtmlEditorConfig.php)
An overview of the available TinyMCE controls can be found here: http://wiki.moxiecode.com/index.php/TinyMCE:Control_reference
Above I added 'ssimage' and 'sslink' (instead of 'image' and 'link') which are SilverStripe specific extensions. Sadly, I don't know where and if these are documented.