I do a fair amount of stock photography, but I am primarily a wedding photographer. I found one of my wedding stock photos on a wedding photographer's website in England. The photo was used in their portfolio section, and their logo was placed on the bottom right side of the image. I emailed the photographer, and he stood his ground.  He explained that he found it on the internet and therefore it now belonged to him. After several emails (rated PG-13) he eventually removed the photo.

I know that many businesses will use stock photos on their site to promote their services, but I definitely have a problem with a wedding photographer using someone else's photos to promote their skills.

Has anyone else noticed anything similar to this?

How frustrating to see another "professional" photographer actually having the guts to slap on their logo on someone else's photograph claiming it's theirs.

These people shouldn't be in business.

Congrats on putting him in his place.

I have to imagine that wedding photography being one of the more popular genres of photography that the masses like to do for money, it is highly likely you'll find a photographer using a stock photo for advertising purposes.  Of course, the 'found' bit is garbage, and just dropping it in a portfolio is misrepresentatiin, but using it in a more promotional aspect should be OK.  Everyone can't shoot everything, and photographers have the right to use stock to fill needs.

Probably "okay" as far as licensing is concerned but ethically in the gutter.

Yeah, with most agencies that's about it. Legally OK if they purchased it. (I realise that the OP was one stage worse, in that the tog had stolen the image, not licensed it from an agency.)
Ethically and legally (in some countries) dubious, as the consumer might reasonably assume that photos on their website were taken by them. Togs traditionally hired models and wedding costumes to get an initial portfolio to show clients.
I guess there's nothing in the T&C to stop togs buying big sizes of wedding stock photos, print them out big, and stick them in their windows in frames. How that would stand legally in different countries, I have no idea. I suspect in the UK, it would be illegal ('intent to deceive').
Consumers are going to have to learn to do searches on companies' website images to check if they purport to the product/service they're considering buying or are 'stock images'. Caveat emptor. The consumer programmes will no doubt start alerting people soon.