September's unusual figures is very possibly due the effect of the beginning of 2007 ( hype ).
At that time accounts doubled per month.
Since 2007II the growth of accounts is in a steady downtrend ( i keep stats ).
It is now at 50% compared to Dec 2007.
Meanwhile user hours grow.
Conclusion: early 2007 signup accounts are spending more and more time in sl, due to addiction.
(it is why we see relatively many 2007 players in high traffic regions in sl).
More virtual worlds are now on the market, so sl is loosing market share.

In other words: it could very well be that the product life cycle of sl is over its peak.

Technically sl is still bumping to it's limits.
62000 online had been seen in Dec 2007, however with huge problems.
At this moment, ~64000 are online as a peak and we are running exaclty into the same technical problems at this very moment.

To me it looks like a dead track at this moment for sl.