This morning I have installed Exchange 2010 SP2.

I must say it was (as expected) a very straightforward process.

The setup wizard passed most pre-requisites first time.

The only pre-requisite which failed was the UM Language Packs.

As I work in the UK I had the en-GB language pack installed.

This was easily done using command prompt in the
<EXCHANGE SERVER INSTALL POINT>\bin directory

I ran;

Setup.com /RemoveUmLanguagePack:en-GB

Then continue with the install.

Once completed re-install the language packs, the desired language pack can be found here;
http://go.microsoft.com/fwlink/?LinkId=231660

Download the correct one and run it and you will have your desired UM language pack installed.

The only other issue I came across was the
“You must close all dialogue boxes before you can close Exchange Management Console” problem.

A quick google pointed me here;

http://smtp25.blogspot.com/2011/07/you-must-close-all-dialog-boxes-before.html

This seems to indicate some problem with IE9.

I added https://localhost  to trusted sites in IE9 and all worked fine.

So as said the install was all good and was straightforward.