Seemingly pushed out quietly by Microsoft as a useful plug-in for anyone with a phone with microSD slot and without the confidence to rely on contact syncing with Outlook/Live/Google etc., the impossibly under-capitalised 'contacts+message backup' is now in the Store to provide vCard backup and restore, perhaps when switching phones. Or perhaps the real use is the other named function, XML-based storage of all SMS and MMS, again for restoring to a new phone. Worth noting, anyway, and it's free, of course.

From the Store description:

Contacts + Message Backup app is a Settings app that enables you to make backup of all your contacts (in VCF format) and messages (SMS & MMS including attachments) to SD card (in XML format) for later restore to same or another Windows Phone.

Backup is stored in 'backup+restore' folder on the SD card.

Interestingly, this plugs directly into Settings, adding a new function to the existing list of options:

Personally, I view SMS and MMS and transient and immediately copy out anything of permanent interest, but I know that some people like to use their SMS store as a vital repository of information - or perhaps sentimental missives from loved ones, so this should be of interest to them.

Anyway, you can grab this new plug-in here in the Store.