byte[] uploadedbytes = null;

//IE:
if (Request.Files.Count > 0)
{
    foreach (string file in Request.Files)
    {
        HttpPostedFileBase hpf = Request.Files[file] as HttpPostedFileBase;
        if (hpf.ContentLength == 0)
            continue;

        uploadedbytes = new byte[hpf.InputStream.Length];
        hpf.InputStream.Read(uploadedbytes, 0, uploadedbytes.Length);

        break;
    }
}

//Chrome/FF: 
else if (Request.InputStream != null && Request.InputStream.Length != 0)
{
    uploadedbytes = new byte[Request.InputStream.Length];
    Request.InputStream.Read(uploadedbytes, 0, uploadedbytes.Length);
}

if (uploadedbytes != null && uploadedbytes.Length != 0)
{
    //handle the upload here.
}

I use this action code with http://valums.com/ajax-upload/ to handle the upload from any browser.

ASP.net MVC: Accept file upload from all browsers.

file

ASP