This signature is recent (1/8/2010) and we are seeing multiple detections.  The write-up is "Trojan.Malscript.B is a generic detection for HTML files infected with a JavaScript that redirects the browser to a malicious Web site that may exploit the browser or download other malicious threats."  When reviewing traffic, we are not finding any redirections.  
Curious if others are seeing false positives on this threat?