Changes have been to the system to comply with Paypal's move to SSL, which come into effect on 30th September.
Order Manager has been slightly updated with:
Better Quick Search filters (includes Invoice ID, Order State, Traffic Medium & Source)
Column totals now show on New Orders, In Progress etc (except All Activity & Abandoned carts)
Traffic Medium & Source displays on an individual order page
Search Results - Display Previous User Searches
You can now set an option to display common user search queries in the drop-down auto-fill section of the header search bar. This uses the last 1,000 user searches as the data source.
To turn this on go to Admin > Products & Store Pages Setup > Search Results Page > tick "Show Top User Queries In Search Autofill Drop-down"
Release 4.1includes some fairly significant re-engineering changes to the way we store visitor data (which allows more accurate analysis of data sources and is also a pre-cursor to future visitor tracking functionality). We have also moved to UTF-8 character coding which better handles foreign language characters and symbols within the content.