S4S Release 1.5.2012.4 adds support for Salesforce API version 24.0 and tweaks a number of retrieval methods in response to customers needs. There are two namespace changes which mean this is a breaking release requiring a recompile of your Sitecore website code. More information on this release can be seen on the release notes page.
The next release will be the eagerly awaited Email Campaign Manager (ECM) integration. The ECM module will have a dependency on S4S but the reverse is not true. If you are currently authenticating your Sitecore website logins from Salesforce contacts, this will continue to work if you also install ECM support.