Question:
My client has a specific case in hand. When client calls ... sales person will insert a phone call to CRM and then need to assssign Task to someone responsible.
Follow Up looks right way to do it, but we have a problem with it. There will be no connection between this Phone Call and Task on a data level. We can’t point person who is responsible for Task to get information about this phone call.
If there would be a connection between them I could use it in Workflow, Callouts or other places. Any ideas?

Answer:
That seems to be either an oversight on Microsoft's behalf or deliberate "functionality" for some reason.
You can't even create custom relationships between different types of activities, so you are probably left with creating a custom solution. But I think there would be an easy way to do this. How about putting a custom ISV button on the phone call form (you can do this now in 3.0!) that calls an aspx page that passsses the phone call data and creates a new task, pre-populating the fields.
There are examples in the SDK of creating tasks, so it should be possssible. Good luck and let us know what you come up with.