The code for exploiting the unpatched VML vulnerability is in-the-wild
for a week or so. This was enough time for Anti Virus, IPS/IDS and
other reactive security products' vendors to create a signature for
the in-the-wild exploit.
So, I put my hand on one of the in-the-wild and tested it using Virus
Total. The results were not so good. Only 10 of 27 Anti-Viruses
detected the exploit on the malicious web page.
Are those signatures generic enough? I've decided to check it out.

I've used 5 simple methods, trying to evade being detected by the signature:
1) I've replaced the location where EIP should jump when the exploit
is activated, with a different valid address.
2) I've replaced the VML element from "rect" with one of the other VML elements.
3) I've replaced the payload with a different valid shell code.
4) I've replaced the namespace key with a random key.
5) A combination of all of the above.

Please note that when I changed the code using any of the methods, the
exploit still worked.

More info: http://aviv.raffon.net/2006/09/25/VMLExploitVsAVIPSIDSSignatures.aspx 

-- Aviv.