You can make your arrangement as clever, quirky or quaint as you like. Find the teacup of your choice, add a saucer (matched or otherwise), tie a ribbon around the handle of your cup, and pop in real of faux-flowers. I made this Easter centrepiece out of a bunny-cup I had as a child. It's handle broke many, many years ago, but a sky blue ribbon hides the worst of it. The saucer, though nothing like the cup has yellow roses which seem to work, especially when you add a fabric rose and some gold and green eggs around the cup.
A teacup centerpiece would also work for a baby shower, or any girly-party. You can even use the teacup centrepiece as the starting point of your party; looking to its patterns and design to inspire your color and motif choices you can use elsewhere in your decorations.
If you're looking for more girly party inspiration, don't forget to have a look at the party planning ebooks for princesses, mermaids, ballerinas and fairies.
For now, I'm off to playgroup with my two pink princesses!