I think this is only the start
When I first heard about MS buying Skype for a ludicrous amount of money, I thought "Meh, another blue-sky venture", but the more I thought about it, the more I realised that this is gonna be big. Really big.
About 18 months ago, we upgraded our phone system due to the company we bought it from going under. We replaced the lot with a new VOIP system.
The handsets were expensive, the software was expensive, the new POE switches were expensive, and the manhours in setting up a complex VLAN to support it... You get the idea.
The reasons we went with a digital VOIP system were many, but included the fact that we could use our existing ethernet infrastructure. As it turns out, the CAT5 wiring is about the only thing that our phones have in common with the rest of our IT infrastructure, and at the end of the day, it still only handles voice calls.
Now imagine Skype being intergrated into Active Directory and Exchange/outlook. The potential savings are incredible. You can buy a USB microphone/speaker in any formfactor you desire for next-to-nothing.
Contact details, routing and out-of-office, all become non-issues, as you already have these set up and configured within AD/Exchange - your phone simply follows your login. Changes and feature adding
Of course, this is all omitting the ADDED features, such as video, conference calling, instant messaging...