Risk(s) in updating libc6

[Gary Chambers]

All,

I have recently migrated a production server from Solaris to Ubuntu
10.04 Server LTS and have recently been informed that some packages
dealing with libc6 need to be upgraded.  My configuration is a normal
installation with the exception of manually compiled versions of
Postfix (2.7.1) and Dovecot (1.2.11).  Given the following details of
my system's current state, can anyone offer insight into whether or
not upgrading the libc6 packages will break anything?  Thank you very
much in advance.

$ lsb_release -a
No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 10.04 LTS
Release:	10.04
Codename:	lucid

$ uname -a
Linux port 2.6.32-21-server #32-Ubuntu SMP Fri Apr 16 09:17:34 UTC
2010 x86_64 GNU/Linux

$ sudo apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages have been kept back:
  linux-headers-server linux-image-server linux-server
The following packages will be upgraded:
  libc-bin libc-dev-bin libc6 libc6-dev libpam-modules libpam-runtime
libpam0g libpam0g-dev libpng12-0
9 upgraded, 0 newly installed, 0 to remove and 3 not upgraded.

-- Gary Chambers

/* Nothing fancy and nothing Microsoft! */