So, I'm still unclear on this. We've determined that you can't connect to 2008 SSIS from 2005 SMS (not a big surprise) but can you connect to 2005 SSIS from 2008 SMS?
According to Buck Woody as noted above:
We don't however limit access to SSIS packages residing in SQL Server 2005 databases (msdb). SSMS 2008 can connect and manage SSIS packages in both SQL Server 2005 and 2008 databases.
However, I still get the error....