Jess, I really like the Easter egg idea!
Zephyr, that's kind of how we did it this time. Just announced to people without anything too clever. The last two pregnancies, I announced with a poem. The first time I said this:
Roses are red,
Violets are blue,
Until March 19th,
I'll be eating for two.
And for DS, I made up this poem and posted it New Year's Eve:
As we ring in this brand new year,
I feel so blessed with my loved ones near.
My dear sweet husband, the love of my life,
Who made me a truly happy wife,
Alia, our sweet little baby girl,
Who came along and changed our world.
And a new little one who remains to be seen,
Until July 26th 2013!