Anyone care to take a swing at this:

What is the difference between a Text Field which has a specified Auto-Enter Calculation and a Calculation Field with a specified text calculation?

When would one or the other be of better use?

Ps. No there is no punch line.

In versions below 7, an auto-enter calculation evaluates when a record is created and never thereafter. A calculation field will re-evaluate whenever referenced fields are modified.

Cool.

Thanks, Queue.

So, do you mean to suggest that in version 7, auto-enter calcs "re-evaluate whenever referenced fields are modified"?

If the 'Do not replace existing value for field' checkbox is deselected, then yes.

Minor update. An auto-enter calculation can be updated by doing a relookup on one of the fields in the calc. This can be very useful to handle typos when a record is first created.