the growth in 2004 was an increase between 50,000-100,000 hours per month. 2005 saw about 200,000 extra hours per month. 2006 was more variable with 500,000 hour swings from month to month. by the end of 2006 the per month hour increase was a million hours. for the past four months the increase has been 3-4 million hours.
my understanding is that SL has a fairly limited world engine with severe scaling problems. id like to work on the next generation engine.
by the way, lord of the rings online launches next tuesday.