Google-logo customized for national events...

This took me quite a bit by surprise, once I opened

In this case, Google celebrates Austria's national day - the 26th of October. This event dates back to 1965. The day's declared purpose is the remembrance of Austria's independence and neutrality. It is also a national holiday.
From a design perspective: The logo is a mere 25kb Jpeg, which is a good payload size. It shows the alp republic with its typical red-white-red striped banding. The fuzzy frame gives the logo a nice historic touch. In practice, the price point of such a logo lies in the order of 1000$, a bit cheaper if you have an in-house designer, as is the case for Google.
From a financial perspective, the investment can be seen as a PR-measure and establishing brand-loyalty, and underlies Google's aim of becoming one of the most valuable Brands in the world.
PS: Google uses geoIP-services to provide geo-targeted services,... like displaying fancy, customized logos to the masses.