Obfuscated web pages

Are any current network based IDS/P systems able to unwind
obfuscated web script to examine the final javascript product?
It would seem they would have to have a javascript engine to
do so and issues with reassembly, iterations, and delays
would preclude them from doing it inline.

Without this capability, it would seem that network based
IDS/IPS is destined to digress to AV style malware
signatures for malicious web server issues and that the only
reliable place to do IDS/P would be on the host.

We've been seeing more and more obfuscated web script and
according to a recently released IBM report, the majority
of exploits are taking this path.

http://www.iss.net/x-force_report_images/2008/index.html

Thoughts?

-- 
Gary Flynn
Security Engineer
James Madison University
www.jmu.edu/computing/security