I came across some issues after upgrading to June 2011 CU and wanted to share this with the rest of you. If any of these issues is a concern, then you should hold off applying June 2011 CU and apply Aug 2011 CU instead. See latest updates here.
There are some issues reported by end users on SharePoint 2010 SP1 and June CU. You may need to verify on your end. Here is the list of the potential issues for your reference from Harry Chen's blog.
1. Security validation error when people picker is on an infopath form.
2. Cannot provision new PWA sites through the GUI. Workaround is to create via powershell. We have verified this is an issues on SP1 and June CU.
3. Unable to open Performance Point Dashboard Designer after SP1/June CU
4. JS Bug in grouped view since SP1?
5. SP 2010 Document Library Column "Show Filter Choices" is not ...
6.Sharepoint Wiki Link Creation Failing
7. SP2010 Column Filter causing Unable to display Web Part error and ...
8. Security validation issue
9. June CU Unique Permissions \ People Picker Issue - This has been confirmed in our environments and Microsoft claimed it will be fixed in August CU.
10. Update-SPProfilePhotoStore not working after SP1 + CU June 2011 - We are having issues to import pictures and it is an issue.
11. BI status list display form missing source list after upgrade