In both Firefox 3.6 and IE 7 (yeah, I know -- corporate IT restrictions) on Windows XP, I am no longer seeing the buttons for formatting, link, etc above the textbox where you type posts. In Firefox I turned off Ghostscript and Stylish (just in case), and I've never customized IE for anything other than default font size.
These buttons were present when I posted a question last night from home (Firefox 10 or 11 on OS 10.6).
I don't know if it's related, but I'm currently also not seeing a preview of this post.