The Microsoft Online Services Team Blog has announced at the end of March 2009 an upgrade to the Microsoft Business Productivity Online Standard Suite.
The following updates are scheduled early April 2009…
Sign In application
“Improved stability and added support for Office Communications Online. Your users will need to install the new Sign In application.” If you want to enable updates you can go to options and select more options.

You can find more information here: Upgrade your Sign In Application.
SharePoint Online privacy links
“Improved privacy link enforcement for international customers.
If you modified your SharePoint master page or uploaded a custom master page, you will need to reset your site definition to the default master page while the upgrade is taking place.
You will be able to customize your site collections again after the upgrade.”

You can find more information here: Update Your Microsoft SharePoint Online Site Collections.
Microsoft Online Services Directory Synchronization tool
“Optimized communication with the service and added compression to reduce synchronization bandwidth requirements. If your company is synchronizing your on-premises Active Directory with Microsoft Online Services, you will need to upgrade this tool by the end of October, 2009.”
You can find more information here: Directory Synchronization Update.
Microsoft Online Services Migration Tools
“Improved stability and performance including support for multiple process threads when migrating from POP or IMAP mailboxes. Upgrading to the new version of the Migration Tools is optional.”
In mid-May the Online Services will require an update to the sign in application so stay tuned…