Now, that clearly does have some similarities to the Batman logo, even though they insist "Our bat is not their bat." In fact, they're correct that the bats are not the same. As someone in the comments on the Consumerist post notes, the actual Batman logos, which have morphed over time, are ever so slightly different from this logo:
But, of course, that doesn't matter. All that really matters is if there's a likelihood of confusion in areas for which DC has the trademark or (potentially) if DC can make a case of dilution. Given how many people see the logo and pretty much immediately think "Batman," DC probably can make a strong "likelihood of confusion" case. The restaurant owners are apprently fighting DC, specifically by suggesting that DC's trademarks on Batman don't extend into the restaurant space, but that does seem like it might be a difficult sell. At best, it's a total crap shoot based on the judge -- and given the cost of fighting a trademark battle over such a logo, this is one where it actually seems like it could make more sense to just change the logo.