I love this cover. It’s by David Frankland, the British artist whose images adorn the covers of Philip Reeve Mortal Engines books, amongst others.
It's from The Bookman, a new steampunk epic by Lavie Tidhar to be published by Angry Robot Books in 2010.
A masked terrorist has brought London to its knees - there are bombs inside books, and nobody knows which ones. On the day of the launch of the first expedition to Mars, by giant cannon, he outdoes himself with an audacious attack. For young poet Orphan, trapped in the screaming audience, it seems his destiny is entwined with that of the shadowy terrorist, but how? Like a steam-powered take on V for Vendetta, rich with satire and slashed through with automatons, giant lizards, pirates, airships and wild adventure, The Bookman is the first of a series.
If you like your steampunk complete with lizard-overlords then it sounds like The Bookman is going to be right up your smog-shrouded street.