UPDATE: Microsoft has a Fix
Microsoft has published a fix, using a diferent approch as used here. They are limiting the number of post parameters to exactly 1000.
To install this update, use Windows Update or visit the link belowe:
This project however can be used for study of the IIS Modules and for future problems.
This is a simple IIS 7 module to avoid the zero day vulnerability which targets string hash colisions discovered by Alexander "alech" Klink and Julian "zeri" Wälde  which is described in a security advisory .
There was a security advisory  of Microsoft describing the problem and a blog post explaing in details the problem .
The Proposed Solution
This solution consists in expection the request input before ASP .net and detecting duplicated form post hashes.
If the form post is "big" ann contains a duplicated hash then the request is rejected.
I used some reference to implement this module. 
This solution needs more work, I only released it now to share the discovery with the community and to receive comments.
I will add more checks and check more data at input, it will be released until the end of the week.
Please send any comments to firstname.lastname@example.org.
The vulnerability is better described in these links:
 http://events.ccc.de/congress/2011/Fahrplan/attachments/2007_28C3_Effective_DoS_on_web_application_platforms.pdf  http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2011-3414  http://technet.microsoft.com/en-us/security/advisory/2659883  http://blogs.technet.com/b/srd/archive/2011/12/27/more-information-about-the-december-2011-asp-net-vulnerability.aspx  http://learn.iis.net/page.aspx/169/develop-a-native-cc-module-for-iis/