Are you using DBD::Oracle? If so, fire up your favorite C compiler. ActiveState is no longer able to publish a ppm of DBD::Oracle so you will have to do it yourself.
More generally speaking, I've found the modules supplied by ActiveState to be inconsistent between releases. Thus, there is no garuntee (unless you have already looked) that all the modules you downloaded with 5.6.1 will be ready packed for 5.8.x. If you don't use ActiveState's PPM for module installation, then this won't matter to you.
So, if you have everything you need in your 5.6.1 environement, I would echo the advice of others and leave well enough alone...
