The following icon packs now have the new Hangouts icon :
Black and Red
Black and Blue
I'll be updating a lot more of my more popular icon packs to include this icon in the next few weeks. Vivid, Vivid v2, Pristine, and Vintage are also planned for today.
If you've downloaded any of these icon packs from my site, just re-download from the My account page and re-install the pack to have the updated version (you can check the changelog within the app to verify this).