Here are the specific to Windows 2008 R2 SP1:
Constraints on the allocation of physical memory represents one of the greatest challenges organizations face as they adopt new virtualization technology and consolidate their infrastructure. With Dynamic Memory, an enhancement to Hyper-V™ introduced in Windows Server 2008 R2 SP1, organizations can now make the most efficient use of available physical memory, allowing them to realize the greatest possible potential from their virtualization resources. Dynamic Memory allows for memory on a host machine to be pooled and dynamically distributed to virtual machines as necessary. Memory is dynamically added or removed based on current workloads, and is done so without service interruption.
Virtual machines running a wide variety of operating systems can use Dynamic Memory; for a complete list, see the “Dynamic Memory Evaluation Guide” at http://go.microsoft.com/fwlink/?LinkId=192444. The guide also discusses Dynamic Memory settings and usage in detail.
Businesses are increasingly looking to leverage the efficiency and cost savings that can come from a virtualized desktop infrastructure. With the addition of Microsoft RemoteFX in Windows Server 2008 R2 SP1, a new set of remote user experience capabilities that enable a media-rich user environment for virtual desktops, session-based desktops and remote applications is introduced. Harnessing the power of virtualized graphics resources, RemoteFX can be deployed to a range of thick and thin client devices, enabling cost-effective, local-like access to graphics-intensive applications and a broad array of end user peripherals, improving productivity of remote users.
RemoteFX can function independently from specific graphics stacks and supports any screen content, including today’s most advanced applications and rich content (including Silverlight and Adobe Flash), ensuring that end users maintain a rich, local-like desktop experience even in a virtualized thin-client environment.
RemoteFX also adds mainstream USB device support to virtual desktop computing, including support for USB drives, cameras and PDAs connected to the client device. RemoteFX also provides a platform for hardware and software partners to enhance RemoteFX capabilities in a variety of possible host, client and network configurations.
To use RemoteFX, the virtualization server must be running Windows Server 2008 R2 with SP1, the virtual machine must be running Windows 7 Enterprise with SP1 or Windows 7 Ultimate with SP1, and the remote client computer must be running either Windows Server 2008 R2 with SP1 or Windows 7 with SP1. To connect to the virtual machine, the remote client computer requires an updated version of Remote Desktop Services (included in the service pack for all editions of Windows 7).
Enhancements to scalability and high availability when using DirectAccess
DirectAccess is a new feature in the Windows 7 and Windows Server 2008 R2 operating systems that gives users the experience of being seamlessly connected to their corporate network any time they have Internet access. In Windows Server 2008 R2 SP1, improvements have been made to enhance scalability and high availability when using DirectAccess, through the addition of support for 6to4 and ISATAP addresses when using DirectAccess in conjunction with Network Load Balancing (NLB).
Support for Managed Service Accounts (MSAs) in secure branch office scenarios
SP1 enables enhanced support for managed service accounts (MSAs) to be used on domain-member services located in perimeter networks (also known as DMZs or extranets).
Support for increased volume of authentication traffic on domain controllers connected to high-latency networks
As a greater volume of IT infrastructure migrates to cloud-based services, there is a need for higher thresholds of authentication traffic to domain controllers located on high-latency networks (such as the public Internet). SP1 allows for more granular control of the maximum number of possible concurrent connections to a domain controller, enabling a greater degree of performance tuning for service providers.
Enhancements to Failover Clustering with Storage
SP1 enables enhanced support for how Failover Clustering works with storage that is not visible for all cluster nodes. In SP1, improvements have been made to the Cluster Validation and multiple Failover Cluster Manager wizards to allow workloads to use disks that are shared between a subset of cluster nodes.