I have some great and unexpected news! It seems that on some websites you can pre-order the first few Tales of Dunk and Egg. Currently, the book is titled A Knight of the Seven Kingdoms. There is no official artwork for the cover or release date yet, but I have the ISBN numbers which are key for searching for it. These are for the hardback edition.
BANTAM / US
HARPER VOYAGER / UK
ISBN 13: 9780007507672
ISBN 10: 0007507674
I don't keep track of 'foreign editions', sadly. I will be sure to update you with official word, but this is something!
These tales take place about 100 years before A Game of Thrones, Book One of A Song of Ice and Fire begins. For the '(fake) history buffs' you get an even further view into the past, as well as the roots and beginnings. So far, it doesn't feel as 'integral' as The Hobbit does Lord of the Rings but they will definitely be enjoyable if you're fans of the Ice and Fire books.