10 is still the limit for Windows Home Server 2011. If you need to back up more, you can set up a second server, or you can use the Windows storage Essentials 2008 R2 or Small Business server 2011 Essentials SKUs instead of the Windows Home Server SKU. The
former will only be available through OEMs (no system builder pack at all), while the latter doesn't have the media handling capabilities, and costs significantly more (around $400 for system builder packaging, IIRC). Both o0f the business related SKUs can
be joined to an AD domain, and the SBS-E SKU can serve as PDC.
I'm not on the WHS team, I just post a lot. :)