The appindicator has been enhanced again in Ubuntu 10.10 Maverick. The new datetime indicator has been introduced in the replace Gnome datetime applet. However, the datetime indicator is quite simple, which drops support for EDS (Evolution data server), location and weather. So you need an indicator api based weather widget, and omgubuntu says there is already such a project of weather-indicator, on launchpad.
However, any attempt to install this package will result in a failure of 404. The ppa is no long maintained (Even the project has been in silent for a long time.) Fortunately, we can still build it from sources.
First, check out the sources with bzr:
bzr branch lp:weather-indicator
Then, change directory into weather-indicator, package it with debuild:
debuild binary
You will get the result in the parent directory:
indicator-weather_10.07.16_all.deb
Then you simply install the debian package with dpkg:
sudo dpkg -i indicator-weather_10.07.16_all.deb
Enjoy !

I did many things to build deb package, in the end I failed…
I only got these words:
dh_pysupport: Cannot detect default Python version
make: *** [binary-install-python/indicator-weather] 错误 9
debuild: fatal error at line 1319:
couldn’t exec fakeroot debian/rules
Okay, I installed Python2.6(default) and Python 2.5(for app engine). In /usr/share/python/debian_defaults, I found “default-version = 2.6″.
So I didn’t know why dh_pysupport told me she “Cannot detect default Python version”.
OMG…
Sorry, I can do little help about packaging. Maybe you should ask some experts.
Hmm.. Nevertheless, thanks for your advice.
BTW, doubanfm plugin of Exaile is outstanding!
A bit of a late response, but ran into the same issue.
Just thought I’d pos a reply here for the next unfortunate soul to run into this issue
You may want to change:
$default =~ s/^python//;
into:
$default =~ s/^.*python//;
in /usr/bin/dh_pysupport (no guarantees, but worked for me).
Problem was that the path returned by readlink is different than expected/matched by regex.