I know I didn't blog about this when I first read about the proposed update, but now that it is real and I can use it, it's definitely worth a mention.
Sun ship a modified version of the panel calendar that supports multiple timezones, very handy when you work in a global organisation and regularly collaborate with people in different timezones.
Admittedly, this doesn't apply too strongly to me in my current role at Sun, but at home, it's very handy to glance quickly and know what time it is in China.
Hopefully Sun will quickly abandon their (in my opinion) third-party changes now that a far superior implementation is available upstream. I present you, the Gnome calendar: