Mirror of Erised

[littlepooh599 at yahoo.com]

No: HPFGUIDX 28216

I've been lurking for awhile and finally decided to post. 
I have a Question regarding when Harry sees his family in the mirror 
of Erised. Lily is crying when harry sees her "crying;smiling,but 
crying at the same time" it says. Are we to assume that where ever 
his parents are now , they  were able to see him too through the 
mirror? Or is this just Harry's DESIRE that his parnets be really 
happy to see him? I'm really curious to see how they handle this 
scene in the movie. I also think this mirror might return again in 
future books.What does everybody think?