Latest releases:
Sputnik Beta 4, Build date: 19.04.2008, Download, Changelog

Older releases:
Sputnik Beta 3, Build date: 09.08.2007, Download, Changelog
Sputnik Beta 2, Build date: 10.03.2007, Download, Changelog
Sputnik Beta 1, Build date: 11.11.2006, Download, Changelog

Sources:
LGPL part, Date: 19.04.2008, Download

Additional toolbars: (Created your own toolbar for Sputnik? Send it to me!)
Toolbar by recedent, Download, Preview