eBook pricing still not equal between stores

I keep hearing that eBook pricing is supposed to start being more equal between stores, yet I haven't really noticed that yet. For example a new book by Stephen Hawking was released today (09/07/2010), The Grand Design. Amazon and B&N have the eBook at $13.61 USD. The Sony Store has the eBook at $15.12 USD. Granted all three stores have a list price of $28 USD, but when have we ever bought from these stores and paid the actual (and IMHO bogus) list price. Here are the links to this eBook in the three stores I mentioned:

Amazon
http://www.amazon.com/The-Grand-Desi...3876355&sr=1-1

B&N
http://search.barnesandnoble.com/The...e+grand+design

Sony
http://ebookstore.sony.com/ebook/ste...00000000270303

I paid more and bought it through the Sony Store because I already have the means and knowledge to convert their ePubs to other formats. But it would be nice if Sony would drop their prices to match other eBook distributors. Yes I know, I could convert the others but I'm too lazy to research the methods.