Skype broke the 2 million active user concurrently online for the first time today. Concurrently I tracked call minutes off the Skype site. Just over 3 million minutes were recorded in an hour. Two numbers that encourage crude Skype maths.
My conclusion again... numbers confirm "communications behavior" is being radically changed. Concurrently every Skyper wants a better headset, handsfree or a cordless handset. They also know the value of these new "minutes" and will spend to make them "better". Confirming while free; users do value them.
Jump to possible conclusion. Mobile operators will have to merge "mobile" with Skype in order to retain "loyalty" to their networks. They can't provide that based on the "usage" profile of Skype adopters. They also can't address the global nature of the calls. Skypers want mobility make no mistake. Mobile operators are going to have to address "SkypeIn".Give me my mobile number for Skype!
Skype Maths:
Three million minutes when 2 million Skyper were online, time one hour. Thus 1.5 minutes called per Skyper. Multiply X 24 hours. Thus approx 30 minutes talking for this hypothetical Skyper. However most Skypers aren't on for 24 hours. So assuming the average online status time is 12 hours then the average daily call time is twice the thirty minutes.
Thus the average Skyper has a relationship of one hour per day with Skype. I should point out that so far these are all averages. So we have many Skypers using it much more... and some much less. Still if we do the 80/20 thing we judge 800k users (20% of 4m probably low) are doing some 3.5 hours on Skype per day. It's simply a mind boggling number to me. While the same number would generate some 8 minutes for everyone else. Still it is those "heavy users" that are "in" the new communications landscape.
Back to the average. At 500 minutes per week we are looking at 2000 minutes per month for the average. Looking at US mobile plans 500 minutes person per month (still a big plan!) is probably the individual comparison plan.
So we have the Skype plan at 2000 minutes. Could Skype behavior be too much for the mobile operators to handle? All this in a few months and we are not even near "always-on".
Skype Minutes:
10/22/2003 100000 concurrent users online
10/25/2004 1 million concurrent users online
02/14/2005 2 million concurrent users online
10/25/2005 ???? 8 million? concurrent users online
Notes:
Makes Skype minutes more important than mobile minutes.
Check minutes and update with a refresh at www.skype.com.
You can also track "seconds" per call via the Skype API. A little program SkypeTools can demonstrate this to you.
While I think Skype only gets minutes when you log off and on it could be notified using another method.
Expect that even those with just a few buddies probably use it for some very long and formerly expensive calls.
. Nov 7-9. San Francisco. 
Feedburner SmartFeed