My understanding of the client profile preview is that it's a stripped down version of .NET focusing on fulfiling the needs of client applications.
However it would be useful to know what is included and excluded from this? Does anyone know?
Here is a list of included assemblies from BCL Team Blog @ MSDN:
BCL, "Core FX," and LINQ
* CustomMarshalers
* ISymWrapper
* mscorlib
* sysglobl
* System
* System.AddIn
* System.AddIn.Contract
* System.Configuration
* System.Configuration.Install
* System.Core
* System.Security
Visual Basic and Visual C++ Language Support
* Microsoft.VisualBasic
* Microsoft.VisualC
XML
* System.Xml
* System.Xml.Linq
Windows Forms
* Accessibility
* System.Drawing
* System.Windows.Forms
WPF
* PresentationCore
* PresentationFramework
* PresentationFramework.Aero
* PresentationFramework.Classic
* PresentationFramework.Luna
* PresentationFramework.Royale
* PresentationUI
* ReachFramework
* System.Printing
* System.Windows.Presentation
* UIAutomationClient
* UIAutomationClientsideProviders
* UIAutomationProvider
* UIAutomationTypes
* WindowsBase
* WindowsFormsIntegration
ClickOnce
* System.Deployment
WCF, Web Services, Remoting, and Serialization
* System.IdentityModel
* System.Runtime.Remoting
* System.Runtime.Serialization
* System.Runtime.Serialization.Formatters.Soap
* System.ServiceModel
* System.ServiceModel.Web
* System.ServiceModel.Install
* System.Transactions
* System.Web.Services
Data Access
* System.Data
* System.Data.SqlXml
* System.Data.DataSetExtensions
* System.Data.Services.Client
Peer to Peer
* System.Net
Active Directory and Enterprise Services
* System.DirectoryServices
* System.EnterpriseServices