I´ve been working for years with CSLA to create business layer objects. Recently I started using XVal 1.0 and XVal.WebForms 0.1 for client side validation.
I started enforcing our rules as DataAnnotations and also in CSLA AddBusinessRules() method. So if a property of type string was required I used a StringLength DataAnnotation and also a CSLA.Validation.CommonRules.StringMaxLength rule in our business object.
I did not like that solution and today I found out about CSLA.Net 3.8 Beta 1 which now supports DataAnnotations. (Find more about this here: http://www.lhotka.net/weblog/PermaLink,guid,7b05be46-15bf-4388-95b6-14f6d7af08e5.aspx)
This is a very important enhancement to CSLA, made by Rocky. I tested it without any issues so now here at HexaSystems we don´t longer need to enforce twice these type of rules.
Note tha this CSLA version depends on assembly: System.Windows.Interactivity which comes as part of Microsoft Expression Blend 3 SDK