Up until now, I’ve never been a big user of Skype. For one, it uses a close-source and proprietary protocol rather than SIP; although this does have the advantage of working over HTTP/HTTPS which means that it’s difficult for hotels to block it (and force you to make calls using their expensive in-room telephones instead). Second, you’re always tied to a PC either with a headset or at the very least some USB wireless telephone (which still needs you to use the client to make changes to contacts etc.).
This is going to change with Netgear’s rather swish, mobile phone style wi-fi Skype phone. No PC. No software. Just wi-fi needed for Skype-to-Skype and Skype-out calling. Buy me 10 when they come out in July: