Hello Michael,
Tasks can be created from various Solution Manager applications : Central System Administration, Issue Management and Work Mode / Downtime Management for the most famous of them.
You will definitely find some additional informations in the AppOps Wiki (Technical Admin°)
http://wiki.scn.sap.com/wiki/display/TechOps/Home
Check also this small summary:
And eventually :
http://help.sap.com/saphelp_sm71_sp01/helpdata/en/31/aa6e844be34c8da2ddff464f3ac765/frameset.htm
Hope this will help.
Sebastien