Close on the heels of the Google SERP Update, now seems Google PR update is on! We are seeing increase in PR for many of our client's sites.
Some fellow members at Webmaster World also confirmed the same.

Few of the IPs where updated PR is currently visible are: 72.14.255.18, 64.233.187.99 & 64.233.167.99.

In order to check it on your PC, you need to make some changes in the host file located in C:\windows\system32\drivers\etc (if you are using Windows).
Opens up the host file with Notepad: (take a backup of this file first)

# Copyright (c) 1993-1999 Microsoft Corp.
#
# This is a sample HOSTS file used by Microsoft TCP/IP for Windows.
#
# This file contains the mappings of IP addresses to host names. Each
# entry should be kept on an individual line. The IP address should
# be placed in the first column followed by the corresponding host name.
# The IP address and the host name should be separated by at least one
# space.
#
# Additionally, comments (such as these) may be inserted on individual
# lines or following the machine name denoted by a '#' symbol.
#
# For example:
#
# 102.54.94.97 rhino.acme.com # source server
# 38.25.63.10 x.acme.com # x client host
127.0.0.1 localhost
toolbarqueries.google.com 216.239.53.104
127.0.0.1 pagead2.googlesyndication.com
127.0.0.1 ad.doubleclick.net

The above means to use the 216 IP address to check Toolbar. Change this (216.239.53.104) to 64.233.187.99 (or any other ip listed by me above) and save your file. Restart your browser (or PC if needed) and you will be able to see these changes.