How To Display the InfoPath Form Version on the Form
Very handy for testing and help desk calls:
Tip: insert form version with the expression:
substring-before( substring-after( /processing-instruction()[local-name(.) = "mso-infoPathSolution"], 'solutionVersion="'), '"')
Source: http://www.nivot.org/2008/09/30/WhyVSTO30VisualStudio2008SharePointWindowsWorkflowAndInfoPathMightGiveYouAHernia.aspx