Looking to increase your web site's "discoverability" on the web to ultimately drive more traffic to your site?
ASP.NET 4.0 has a few new features coming to help you improve the SEO aspects of your web site:
Page.MetaKeywords and Page.MetaDescription properties
One of the nice improvements with ASP.NET 4 Web Forms is the addition of two new properties to the Page class: MetaKeywords and MetaDescription that make programmatically setting the “keywords” and “description” <meta> tags within the <head> section of your HTML much easier and cleaner.
URL Routing support for ASP.NET Web Forms
With ASP.NET 4.0, URLs can now be mapped to both ASP.NET MVC Controller classes AND ASP.NET Web Forms based pages. You can even have a single application that contains both Web Forms and MVC Controllers, and use a single set of routing rules to map URLs between them.
ASP.NET 4 introduces a new Response.RedirectPermanent(string url) helper method that can be used to perform a redirect using an HTTP 301 (moved permanently) response. This will cause search engines and other user agents that recognize permanent redirects to store and use the new URL that is associated with the content. This will enable your content to be indexed and your search engine page ranking to improve.
Check out Scott Guthrie's blog post below for all the details: http://weblogs.asp.net/scottgu/archive/2010/01/05/asp-net-4-seo-improvements-vs-2010-and-net-4-0-series.aspx