We officially support IE7 and IE8 in Aloha. I say officially, because, although it does seem to work, it doesn't work very well (at all). IE does some weird stuff with the DOM, especially inside a contenteditable (certain combinations of DOM elements completely mess up the structure if it's inside a contenteditable, but not if it's outside).
Out of curiosity is it working in IE8 for you? Doesn't appear to fully work for me using IE8 on XP. The editor buttons and most of the page don't appear.