Script for when system was last updated

[Nigel Henry <cave.dnb2m97pp@aliceadsl.fr>]

Not long ago I booted Lenny, and discovered there were more than 800MB of 
updates waiting to be installed, and not a bunch of fun on dialup. Looking at 
my saved history files, I hadn't updated for nearly 2 months.

I save the history from the updates in /home/user_name/history-files, and 
label these according to the date when I updated. For example 20080528.

Could someone suggest a script I could put in ~/.kde/autostart that would put 
up an xmessage saying when the system was last updated, when I boot up Lenny?

Much appreciation to all you scripting gurus out there.

Nigel.