Connect to SQL Server 2012 Database from 2008 Agent Job containing 2008 SSIS Package
Yes, most likely. This is a short answer, but it sounds like you are really just asking - Can a job on SQL Server 2008 calling an SSIS package built on 2008 connect to a database in SQL Server 2012 and do some work within that database?

SSIS can connect to many OLEDB/ODBC compliant connections. You could, for instance use an SSIS 2008 (or 2005 or 2012) Package to read data from one Oracle database, do some transformations and the write the results of that to another Oracle database, never talking to SQL except the SSIS engine.

So an SSIS package in 2008 should be able to work with a connection to 2012. Some caveats like - if you are using a deprecated command structure in an execute SQL task - it will fail.. Or test it and verify first. But this should work, if you are just asking if - from within the SSIS package can I talk to SQL Server 2012.