I posted a book and see that there is a request for this book in the wish list  category. Is there anyway for me to notify the requestor that I have posted this book?

No.  If the ISBN of the book you posted matches the ISBN of the book this person is requesting, then PBS will send a notification.  You could post in Book Bazaar that you have this book available.

I would compare the bindings and see how many copies of my version there are first.  You can see how many of yours are posted by putting it on your reminder list.  If there's a ton of yours posted and the binding is different then the WL-then those people don't want your version. If the WL is for large print, hardback or audio and yours is a paperback that's heavily posted then most likely those people reallly want that version and they are willing to wait.

If there aren't many of your posted and the binding is similar (the WL isn't for audio or lrg print) then I'd tag the WL book with the ISBN of yours.  "xxx # posted under ISBN XXXX".