The new SalsaAPI class now has feature parity with salsa_api_query(), so salsa_api_query() is now deprecated. Please update your modules to use the methods in the new class, which are faster and more robust. See the docblocks in salsa_api.inc and DEVELOPERS.txt for full information on using the new methods.
The 7.x-3.x version. Significant refactoring was undertaken, however the basic 7.x-2 feature sets are stable and in use on a handful of production sites.