Thanks for the suggestions, Paul. I like the idea of moving the bracketed part to the front of the title.
We do spell out in the Sponsored Post guidelines, linked from the article, that the posts are written by the advertiser, as we thought that was better/more credible than us being paid for our opinions. I’m not sure about other sites, but I know Mashable does the same thing. We’ll take a look at it, but it does make me feel a little uneasy about how we’d be perceived if we were getting paid to write the copy ourselves. Maybe the answer is to move the explanation about who wrote it from the Sponsored Post guidelines page (which is linked to in the article), right into the article header itself.
Anyway, some great points! Thanks for the input.