First add-in is USB Easy Transfer.

This allows Data Vault users to have the contents of attached USB drives – both flash-based and hard disk based – to be copied over from the drives, allowing the data on the USB drives to be offloaded, and said drives reused. The FAQ below details the uses of this.

Easy USB Transfer FAQ

Q. What is the HP Easy USB Transfer add-in?
A. HP Easy USB Transfer is a free add-in that allows you to copy or move files easily between a USB drive and the HP MediaSmart Server or the HP Data Vault.  Transfer files to or from the USB drives – either way.

Simply plug  your USB hard drive or flash drive directly into any USB port on the HP MediaSmart Server or the HP Data Vault.  Click on the HP MediaSmart Server or HP Data Vault icon on your desktop to open the Web site (User interface), and then click on the Easy USB Transfer icon located at the right.

From the Easy USB Transfer interface, drag a single or multiple folders or files from the USB drive to any folder on the Server, or from Server folder to the USB drive to initiate the Copy.  Hold the shift key to Move the file or folder.  You can also right click on a file or folder and Cut/Copy, Paste.

Once the transfer is initiated, no connection through your computer is required - you can disconnect or turn off your computer and the transfer will complete without a computer connected.

Q. Is HP Easy USB Transfer exclusive to HP, what products does it work with?
A. Yes, HP Easy USB Transfer is an HP written add-in for the HP MediaSmart Server or HP Data Vault. Easy USB Transfer works with 3.0 software from HP, including the EX490, EX495, X300, and X500 series. 

Q. How do I get the HP Easy USB Transfer add-in?
A. Customers can get access to Easy USB Transfer through the HP MediaSmart Server and HP Data Vault Add Software page at http://h41112.www4.hp.com/promo/mediasmartserver/index.html .   The Add Software page is also accessible through the WHS Console on EX49X series products.

The customer will download the add-in .msi file to their client computer, and then copy the file to the \\Software\Add-ins folder on the Server.  The customer will then go into the WHS Console and Install the Add-in through the Settings menu.

Q. What is a Windows Home Server software add-in?
A. Add-ins are supplemental programs that extend the functionality of Windows Home Server. These applications can be added to and managed by Windows Home Server via integration into the Windows Home Server Console, running as a web service on Internet Information Server, or operating in a client/server fashion.

http://msdn.microsoft.com/en-us/bb981194.aspx

Secondly, the previously-announced TiVo add-in.

Targeted at North America only, this update will allow customers to schedule series recordings of their favorite programs and have them automatically copied over to their MediaSmart Server or Data Vault.

These add-ins are available now.