Earlier today, AllThingsD's Peter Kafka and PRNewser's Joe Ciarallo received the same invitation to ad:tech New York, offering some freebies in exchange for coverage.

The offer asked for "no less that 3 posts" about the event, either on Twitter, Facebook or the blog. Nice to know that Twitter and Facebook are as valuable a blog post, despite being loads easier to accomplish. They offer some suggestions for post topics, like "interesting sessions at the event."

"Is my work nearly worthless? Or pretty valuable?" asks Kafka of the offer. "Three posts is a little less than a day’s work for me. ad:tech says that's worth either $35 (a free expo pass) or up to $558 (35 percent of the highest price for an ad:tech conference pass). That's a big swing!"

Ciarallo (PRNewser is our sibling, mind you) found out that the email came not from ad:tech or their PR firm, Edelman. Rather it was from a third party, who he did not name, but had helped "ad:tech with a few specific things." What else, one wonders.

"We point this out not only because it's bad practice, but it seems to be on the rise," writes Ciarallo. "The number of emails we receive that are similar to this one have been increasing."

See the email, here.

This could all be solved with CMP.ly, a new tool that makes it easy to distinguish the paid from the unpaid.

More: "IAB to FTC: Your New Regulations Could 'Muzzle' Speech"