Sure, there could be 30,000,000,000 Earths in the Milky Way. But who's counting? What would cause a planetary body to qualify as "an Earth"? Would it have to be compatible with Terrestrial life, or just have a rocky surface, an oxidizing atmosphere, and liquid water? This sort of thing makes "political science" look positively scientific, by comparison.
Personally, I won't be satisfied unless they have HDTV and Blockbuster Videos on every corner.
Freedom, Wealth, and Peace,
Francis W. Porretto
Visit The Palace Of Reason: http://palaceofreason.com
If they lack these basics, don't worry. They shall have Blockbuster as soon as we get there.