After listening to the 2007 Q3 eBay investor's conference call...

Start with a Skypeku:

Users calling less
losing traction for a year
Skype's mojo falling

From 9.1 to 7.5 billion minutes per quarter, an 18% drop of 1.6 billion minutes this year.

Another Skypeku:

Ghostly Skype accounts
dilute per capita stats
how many active?

Skype's "number of user accounts" include accounts of dead people, abandoned accounts, space aliens, defections. 

"Simultaneous accounts connected to the Skype network" is more meaningful, closer to "active user accounts." Out of everything, simultaneous online is the only metric that seems to be improving. And this last million of growth is the slowest since the first million.