rpm -qa --last will return all installed rpm packages with their installed time. The last installed packages will be at the top of the list.
rpm -qa --last | less is will return all installed packages with their install date. Less allows you to scroll through the results.
rpm -qa --last | tail -n [lines] will return the last 5 packages. Replace [line] with any number you want, in my case 5 for file lines.
[root@bambee root]# rpm -qa --last | tail -n 5<br /> termcap-11.0.1-17.1 Tue 09 May 2006 03:02:53 PM MYT<br /> setup-2.5.27-1 Tue 09 May 2006 03:02:52 PM MYT<br /> filesystem-2.2.1-3 Tue 09 May 2006 03:02:52 PM MYT<br /> basesystem-8.0-2 Tue 09 May 2006 03:02:52 PM MYT<br /> redhat-logos-1.1.14.3-1 Tue 09 May 2006 03:02:51 PM MYT
rpm -qa --last | grep [package name] will return the install date for a specific RPM package. In my case the apache web server [httpd]
[root@jumbo root]# rpm -qa --last | grep httpd<br /> redhat-config-httpd-1.1.0-4.30.2 Sat 29 Mar 2008 09:03:40 PM MYT<br /> httpd-2.0.46-70.ent Sat 29 Mar 2008 08:58:19 PM MYT