This is the first time in 8 years that Google does not a specified St. Patrick's Day logo on the Google.com home page. Google does have a special logo on Google Ireland but not on Google.com. Speculations abound about Google not posting it globally because of the enormous crisis in Japan, yet no one from the Google camp has confirmed anything yet.
Here is the Google St. Patrick’s Day logo on Google Ireland:
And here is 2010's St. Patrick's Day logo offering from Google:
If Google is too busy to get a logo together for the holidays, they should give Pixellogo a call. We have some logos kickin' around.