9/17/09–Users of the free ArcGIS Online map services now have the option to access these services via an HTTPS connection. The use of HTTPS to access the map services encrypts the communication with the server and provides an added level of security for requests. There is some performance overhead to an HTTPS request, so it’s not recommended when a standard HTTP connection is sufficient.
To use an HTTPS connection, ArcGIS users can connect to the free ArcGIS Online map servers through the standard URLs using the HTTPS protocol (i.e., https://services.arcgisonline.com/ and https://server.arcgisonline.com/).
HTTPS is supported through ArcGIS Desktop, ArcGIS Server .NET Web ADF, ArcGIS Server Java Web ADF, and ArcGIS API for Microsoft Silverlight. Support for the ArcGIS API for Flex and the ArcGIS API for JavaScript will be added in the next few weeks with new releases.