In our previous post,  for those of you  running Office Web Apps hosted on-premises,  we covered which service pack and cumulative updates to install and in what order for SharePoint.  However, we didn't include a scenario with the language packs updates.  We've had some questions as to where those fit in.  So without further ado - here is our recommendation depending on your environment:

If your environment includes:

Apply these updates:

SharePoint Server 2010 + Office Web App Farm + Language Packs

Step 1: SharePoint Server 2010 SP1: http://support.microsoft.com/kb/2460045 

Step 2: Office Web Apps SP1: http://support.microsoft.com/kb/2460073 

Step 3: SharePoint Server Language Pack SP1:  http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=26621 (Download and apply the SPs for the language packs you have installed) 

Step 4: SharePoint Server 2010 June CU: http://support.microsoft.com/kb/2536599 

Step 5: Office Web Apps June CU: http://support.microsoft.com/kb/2553919/

(NOTE: The Office Web Apps updates for Excel Web App are included in the SharePoint Server 2010 June Cumulative update.) 

Step 6 - Optional patch:

2553935 Description of the Office Web Apps hotfix package
(wacproof-sv-se.msp): June 28, 2011 *NOTE: Only needed if you have Swedish language pack installed. 

Step 7: Once you have finished applying all the updates, run the SharePoint 2010 Products Configuration Wizard or "psconfig –cmd upgrade –inplace b2b -wait” one time on every server in the farm.

SharePoint Foundation 2010 + Office Web Apps + Language Packs

Step 1: SharePoint Foundation 2010 SP1: http://support.microsoft.com/kb/2460058 

Step 2: Office Web Apps SP1: http://support.microsoft.com/kb/2460073 

Step 3: SharePoint Foundation 2010 Language Packs SP1: http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=26629
(Download and apply the SPs for the language packs you have installed) 

Step 4: SharePoint Foundation 2010 cumulative update http://support.microsoft.com/kb/2536601 

Step 5: Apply the following 3 patches for Office Web Apps:
 2553924 Description of the Excel Web App hotfix package
 (xlwacwfe-x-none.msp): June 28, 2011 - http://support.microsoft.com/kb/2553924 

2544029 Description of the Excel Web App hotfix package
(wacmui-xx-xx.msp, xlwacmui-xx-xx.msp): June 28, 2011 - http://support.microsoft.com/kb/2544029 

2553919 Description of the Office Web Apps hotfix package
(wacwfe-x-none.msp): June 28, 2011 - http://support.microsoft.com/kb/2553919 

Step 6 - Optional patch:

2553935 Description of the Office Web Apps hotfix package
(wacproof-sv-se.msp): June 28, 2011 *NOTE: Only needed if you have Swedish language pack installed 

Step 7: Run the SharePoint 2010 Products configuration wizard.

For more information, see the Microsoft SharePoint Team Blog post “Service Pack 1 for SharePoint 2010 Products is Now Available for Download”.  Note that SharePoint Server 2010 SP1 includes the SharePoint Foundation SP1 and that SharePoint Server 2010 Language Pack SP1 includes the SharePoint Foundation 2010 Language Pack SP1.  So if you are running SharePoint Server 2010, installing the SharePoint Foundation 2010 service packs are optional.