OK, I just realized that maybe when you said Notes fields, you meant Notes fields - not Notes themselves.

I tested this in 8.0 (864), and here's the scoop.
You
can create a hyperlink inside a Note field, as above.
The link is
not displayed as a link in a diagram, nor is it clickable.
If you switch on formatted Notes for the Element, the link
is displayed properly, but is
not clickable.
If you create a separate Note and link it to the Element's Note, again, the link
is displayed properly, but is
not clickable.
In other words, it doesn't work in 864.
Sorry about my confusion there.
Cheers,
/Uffe