have you figured this out? If not please provide more detail so it can be properly entered in Gemini.

The announcements fonts are covered by two classes:

The announcement title:
.SubHead{
font-family: Verdana, Tahoma, Arial;
}

The announcement description:

Should be affected by the .Normal{} class for your skin - otherwise, or to override conflicting classes, use

.DNN_ANN_Description{
font-family: Verdana,Tahoma,Arial;
}

You'll find that the announcements module automatically loads its own css, which is overridden by the skin stylesheet, if relevant. The default announcements styles shouldn't have any font family assigned.