I would say NO.
My D has just gone through something horrible...my brother (her uncle) invaded her My Space "space" -- made photocopies of what he disapproved of, and mailed them to all our relatives on one side of the family. I would never, ever, have anticipated this.
Her choice was to make her My Space private, so only people she specifically invite can log in and see it.
I would not add a relative to space I enjoy sharing with friends.
Given my indiscretions and garrulousness of the past, I'm just grateful I am past the age when social networking via these kinds of sites is likely for me...
Maybe you could say, My policy is not to open my MySpace page for relatives, but if you'd like to get closer, let's find another way.
Errgh. DO TRUST YOUR INSTINCT.
xo
Hops