Don't worry this is not illegal :) I got those keys from the MSDN Blogs http://blogs.msdn.com/opal/archive/2009/11/21/sharepoint-server-2010-beta-key.aspx for the Beta Version.
I think it will help if you can't find a key/serial for evaluating the product.
SharePoint Server 2010 Beta(Enterprise Client Access License features) product key:
PKXTJ-DCM9D-6MM3V-G86P8-MJ8CY
BV7VC-RMR6B-26P6Y-BTQDG-DX2KQ
Enjoy the new SharePoint...
