Go and read http://savagecritic.com/ (and you need to read both http://savagecritic.com/2009/07/neil-gaiman-at-comix-experience-719.html which is the story behind the signing (and has some photos of me in 1989 with the most remarkable mullet) and http://savagecritic.com/2009/07/neil-gaiman-at-comix-experience-719_08.html which is the facts.
Short version, I'm doing a signing at Comix Experience on on Sunday, July 19th from 11 AM to 12:30 PM. And because time is limited, it's limited to 100 people. Brian Hibbs decided that the easiest way to pick the 100 people was to presell them copies of the WHATEVER HAPPENED TO THE CAPED CRUSADER hardback, which will be out then.
Preorders for the book can be taken immediately by visiting Comix Experience at 305 Divisadero St. (at Page) in San Francisco, or by calling 415-863-9258 from 11-7 Monday-to-Saturday, Sundays 12-5, PST.
And my Metamorpho Page with the brilliant Mike Allred is out in Wednesday Comics -- details of what this thing is at: http://comicbookresources.com/?page=article&id=21941