IIS 7.0 and RequestLimitsElement
As we all know in ASP.NET we can configure the maximum length of the request using httpRuntime's "maxRequestLength" attribute (By default this is set to 4KB and SharePoint uses 50MB as a default value). While this setting works with IIS 6.0, in IIS 7.0 a new attribute "RequestLimitsElement" needs to be configured as well to allow uploading files larger than 30 MB through HTTP.
More information can be found here and KB944981.
