ASP.NET MVC Custom Error Handling Application_Error Global.asax?

I have some basic code to determine errors in my MVC application. Currently in my project I have a controller called Error with action methods HTTPError404(), HTTPError500(), and General(). They all accept a string parameter error. Using or modifying the code below.
What is the best/proper way to pass the data to the Error controller for processing? I would like to have a solution as robust as possible.

Asp.Net Forms Authentication when using iPhone UIWebView

I am writing a Asp.net MVC 2 application that uses Forms Authentication and currently I am having a problem with our iPhone application in regards to the authentication/login over the web. We have developed a simple iPhone app that uses the the UIWebView control. At this stage, all the app does is navigate to our Asp.Net website. Simple, right? The problem is, that the user cannot get past the login page. The repro steps are: