During yesterday's keynote it was revealed that there have been over 4.5 billion apps downloaded from Android Market. It was further revealed that it took 2 years to reach the first billion downloads, but only 60 days to get the last billion. It doesn't matter how you do the math, that's huge.
In today's presentation by Eric Chu he showed the slide about that demonstrates the 8x growth in 2010 downloads compared to 2008 & 2009 combined. Needless to say that with the growth in popularity of Honeycomb tablets and the many new phones coming to carriers around the world expectations are high for continued rapid acceleration in 2011 and beyond.
Then, factor in the 99 additional countries that are gaining paid app support before then end of the month and 2011 really begins to shape up as the year of the Android app downloads.