I would like to highlight some of the more important changes about sarge r2. They have been placed in the official announcement not as noticeable as I would have hoped.
Notable Changes
---------------

Sudo has been changed to not propagate all environment variables to
subsequent programs to avoid security risks.  This change might affect
software that uses sudo.  Please see /usr/share/doc/sudo/README.Debian
for more details.


Miscellaneous Bugfixes
----------------------

This revision adds important corrections to the following packages.
Most of them don't affect the security of the system, but may affect
data integrity.

	affix-kernel           Fix build failures with sarge's kernel
	
	backuppc               Fix possible backup archive corruption and
			       possible data loss when changing the
                               configuration file
	
	cernlib                License problems, repackaged
	
	cyrus-imapd            Don't remove mail data on package purge
	
	cyrus21-imapd          Note cyrus-imapd data loss on package purge in
                               upgrade documentation
			       
	evms                   Fix address stack corruption leading to possible
			       data loss when activating degraded RAID-5
                               volumes
			       
	exim4                  Fix mail delivery problems to hosts with AAAA
                               DNS records and unbalanced DNS
			       
	f-prot-installer       Adjusted to work with recent releases
	
	fai                    Fix setup of lo device, replaced hardcoded name
			       of debian distribution in fai-cd, add missing
                               packages when calling fai-mirror

	glibc                  Update timezone data, fix NPTL for x86_64 (amd64)
	
	leafnode               Fix security issue (CVE 2005-1911)
	
	libchipcard            Don't remove user account on package purge
	
	mutt                   Fix possible attachments data loss

	perl                   Fix problem with utf-8/taint interaction
	                       Fix possible malloc-to-death bug, #227621

	rssh                   Fix security issue (CVE-2005-3345)

	slune                  Adjust to security fix in py2play, #326976

	sodipodi               Fix segfaults on 64-bit architectures

	tar                    Fix inability to work with remote devices
                               on non-i386, #356657