Version:           0.9 svn 1029786+ag1 (using KDE 4.3.2)
OS:                Linux
Installed from:    Ubuntu Packages

Testcase:
- kcmshell4 kcm_networkmanagement
- Add new OpenVPN connection, setting the user name to "foo" (X.509 With Password)
- Check the network connection config file in ~/.kde/share/config/apps/networkmanagement, see that the username is properly stored.
- Edit the new vpn connection, see that the username was loaded as your linux account's username.

The problem here seems that d->setting->userName() (from openvpnwidget.cpp, in the NM_OPENVPN_CONTYPE_PASSWORD_TLS case of the readConfig() function) is returning the linux account's username rather than the stored username. I also inserted a kDebug() into the code that confirms this:
kcmshell(9509) OpenVpnSettingWidget::readConfig: username ==  "jonathan"
^ should be "foo"

It gets all a bit out of my depth after that, so I do not know why it is not returning the stored username. Hopefully this is enough info shed some light onto the fault.