While there's no real "standard" most calibers use the same threads (with some exceptions. For example, all of the .22's I've seen are 1/2x28 as well as 9mm Glock's and M&P's. However- some of the other brands in the same caliber will use LH threads or a 3-lug mount.
However, most suppressor companies offer pistons in several different thread pitches. That way you can have a .45 can and to run it on a 9mm gun all you have to do is swap the piston to the one with the correct pitch.
To answer your question a little more directly, I have the Gemtech thread adapter that fits walther p22's and the M&P .22. Pretty sure that's what you're talking about and it's 1/2x28. MOST (if not all) dedicated 22 long rifle cans will work on that.
Edit to add:
From TacSol's website:
"Available with or without flutes in a standard barrel or threaded end barrel** in ½” x 28 TPI."
Check out this link:
MANY rimfire suppressors, all of which are 1/2x28.
Hope that all helps.