I've just upgraded to 1.2.3 and Firebug is reporting "missing ; before statement" on the line that starts:
document.getElementById('wphead').innerHTML = '<h1><span id="blog-title"
which is in the dashboard switcher.
The problem is caused by the fact that one of the blogs is called Steve's Rambings and the ' gets Javascript all confused!
To fix this line 81 needs changing to:
$out .= '
<li><a>domain . $blog->path . 'wp-admin/">' . addslashes($blog->blogname) . '</a></li>
';
I'll raise this in tracker.