Sharepoint 2007 is built on top ASP.NET 2.0, and subsequent versions will follow this path - read more about it on [url=http://weblogs.asp.net/scottgu/archive/2006/04/30/SharePoint-2007-_2D002D00_-Built-on-ASP.NET-2.0-.aspx]ScottGu's blog[/url]. Since MonoX uses standard Web part architecture ([url=http://msdn.microsoft.com/en-us/library/e0s9t4ck.aspx]more on ASP.NET Web parts[/url]). To quote Scott,
... you can now use ASP.NET 2.0 features (Forms Authentication, Master Pages, Membership, Site Navigation, New Data Controls, etc) when building SharePoint sites. This is true for both the new Windows SharePoint Services 3.0 version (which will be a free download) as well as Microsoft Office SharePoint Server 2007 (which costs money).
One of the cool developer scenarios is the ability to create your own Web Part controls that can be used in both SharePoint sites, as well as regular vanilla ASP.NET 2.0 applications. This allows you to re-use all of the built-in SharePoint features for collaboration, document sharing, and content management - while also adding your own custom UI and behaviors (for example: if you want to integrate custom data editing and reporting to a site).
[url=http://www.codeguru.com/csharp/.net/net_asp/webforms/article.php/c12293/]Sahil Malik[/url] and [url=http://weblog.vb-tech.com/nick/archive/2006/05/10/1563.aspx]Nick Swan[/url] wrote two nice articles with practical tips on how to use ASP.NET 2.0 Web parts in SharePoint 2007.