If you want to sync your N900′s clock with an NTP server you can download the ntpdate package for Maemo 5 from here:
install it as root:
dpkg -i ntpdate_4.2.4p4+dfsg-micro_armel.deb
You can sync your clock manually (while you are connected to Internet) from the shell by typing as root:
ntpdate pool.ntp.org
Example result: 28 Nov 15:46:02 ntpdate[16999]: adjust time server 78.128.1.18 offset -0.076669 sec
or/and you can install this widget, so you can do it from your menu with just one click when you have access to Internet:
This widget requires ntpdate to be already installed and it is syncing your time with the NTP servers in pool.ntp.org
Download from here:
http://tonev.net/n900/sync-time-ntpdate-widget_0.1-micro_armel.deb
install it as root:
dpkg -i sync-time-ntpdate-widget_0.1-micro_armel.deb
You should see it now in your menu.

