There are at least three distinct roles often referred to as PM: project manager, product manager, and program manager. I got tired of this ambiguity.
"Hi, nice to meet you. I'm a PM and I'm new to town."
"Oh cool! I know this great Meetup you should join."
Two weeks later: "Uhh, dude, this is a project management meeting. I'm a product manager."
I'm now quietly campaining to use PjM, PdM, and PgM instead. Add a T at the beginning to stand for "technical".
(The nifty thing is that I just started doing this at the office one day and people started to adopt it, no cajoling needed.)
The lowercase middle letter is just a typographical effect; thus I'd call a technical product manager "tee pee dee em".
It's a couple more strokes of the tongue, but vastly better if you're a fan of comprehension.
For product marketers, I tend to use PMK, and PMM is in common use. I think most practicioners would get what you mean by either of those, but if there's a PMK in the audience, feel free to yell out your favorite mini-moniker.