Well, while I approve of the decision as far as it goes, Maryland Circuit courts are courts of equity, and given the blatant abuse of prosecutorial and police powers in this case the court should have used its equitable powers to throw out all charges, not just the wiretapping charge. This victim has been put through enough by the state already.
I see two levels to this. First of all, it should be legal to record any conversation to which you are a party. Second, even if it's not, it should always be legal to do so if the other party is a public employee performing their official duties. With that in mind, I'm disappointed that the ruling seems to have been based on the fact that the conversation was held in a public space and cannot be considered private. Even if it's not in a public space, it should be legal to record a conversation with a public employee performing official duties.
I'm still disappointed that the conduct of the police officer is still being overlooked. The entire reason there was so much butthurt in this case is because the officer was clearly in the wrong and got caught on camera doing it.