I love Google Plus Communities. I use them with my students to help build community and share announcements. Since I am making announcements to my class it can be helpful to emphasize certain words or phrases.
Put asterisks around the word or phrase you want to have bolded. Make sure there is no space between the asterisk and the letter.
*This phrase will be bold*
Flanking the word or phrase with the underscore will allow you to italicize in Google Plus.
Dashes on either side of the word or phrase will create a strikethrough.