Tom Hollander has posted what the initial feature list of changes for the next version of the Enterprise Library will consist of.  One item on the list made me think that they have really taken on a challenge.  There is a new application block proposed for validation.  I look at things like the client side validation control and the business rule scheme that Rocky uses in CSLA.NET and I just wish I could be a fly on the wall when they go to build this.  It is going to be fun to come up with a solution that is flexible enough to cover a large number of scenarios and still perform.  Good luck guys.