As subject header... Many of the Matlab apps submitted to file exhange by users look very interesting and I'd love to try them, but I'm having no luck installing.
The documentation I can find only makes mention of apps (and the app tab) in 2012b, but I see comments on at least one app submission page indicating I can install in 2012a.
Can I install and use apps in my copy of 2012a, or am I out of luck until my college move to b?
Sorry, you need to have R2012B to run apps.
It depends. Many of the apps don't depend on this latest release. For example, none of mine do since I developed and uploaded them when I had earlier releases. Even apps developed on R2012b might not require R2012b and might run fine on any number of prior versions. Download it and give it a try. I would say that the vast majority of apps in the File Exchange do not require R2012b.