Just downloaded the new Skype which introduced desktop sharing. I can now cut out Webex for internal meetings and discussions and have conference calls on skype.
I use WebEx heavily for internal meetings, trainings and other types of virtual gatherings.
Desktop sharing isn't required in all virtual gatherings, but is a necessary about 60% of the time. If it is built in and easy to do I will do more often.
Now skype is positioning itself against Webex, GoToMeeting and other virtual meeting tools. Webex is at a nice price point too, FREE.
Definitely something I can't require of all clients and people I interact with, but for internal operations I can definitely require its usage.