I just tested [955] today and it seems that the visual editor is broken. It doesn't even load on FireFox? 2.0.0.3 and loads with errors on IE 7.
From the web server logs I could at least see some wrong image URLs:
[error] ... File does not exist: /wwwhome/wp-includes/js/tinymce/themes/advanced/images/{$lang_b
old_img}, referer: .../wp-admin/post-new.php
[error] ... File does not exist: /wwwhome/wp-includes/js/tinymce/themes/advanced/images/{$lang_i
talic_img}, referer: .../wp-admin/post-new.php
[[error] ... File does not exist: /wwwhome/wp-includes/js/tinymce/themes/advanced/images/{$lang_u
nderline_img}, referer: .../wp-admin/post-new.php
The IE JavaScript? error is "formElement.value is Null or not an object" (line 2035, char 3).