Pix 'n Love are one of the many reasons I envy France sometimes (one other reason being their animation scene). They are a highly prolific publisher of gaming related books including many charting the history of consoles, game developers and franchises, most of which so far have focused on Nintendo and Hudson works. Early next year however they have their sights set on Sonic!
The History of Sonic the Hedgehog is currently up for pre order at their website for 30€ Euros and will be a massive 300 pages long! At this moment it looks like it's only going to be sold in French but some of their books have been translated into English before so here's hoping! Even with the language barrier however it still looks like it's going to be full of great full colour art from all over the history of Sonic; judging from this preview page below even as miscellaneous as Tails and the Music Maker!
Just because Generations has arrived doesn't mean the 20th Anniversary celebrations are ending! If we hear anything about a English translation of this book we'll of course let you know, at least after I've pre-ordered myself a copy anyway.
UPDATE: Well what do you know! Turns out Pix 'n Love will be releasing an English version at the same time! It will be available to pre-order from their English website in a few weeks!