Provocraft have announced that they will no longer be releasing updates to Design Studio. This includes both program updates and Content (cartridge) updates.
Here's their announcement:
"In order to focus our attention and resources on creating and improving the Cricut® experience, we will not be providing further updates to the Cricut DesignStudio® software. In addition, any cartridges released after April 11, 2013 will not be updated to appear in the Cricut DesignStudio® software. We will still offer support, but there will be no additional content updates for the Cricut DesignStudio® software."
The final content update (v130401) was released early April 2013. That update contained the following cartridges:
Boho Graphics Iron On
Brooklyn Iron On
Creative Memories Tiny Treasures
Folk Art Festival
Something to Remember
Teresa Collins December 25th.
Any cartridges released after the above won't be added to DS.
You can download the above update from: http://www.cricut.com/home/support/CDS
(Select Cartridge Update 2.)
Any previous cartridges will be found in the Program Update (cartridges released up to Nov 2009) and Cartridge Update 1 (cartridges released after Nov 2009.)