the first version of Mathematica based on the complete Wolfram Language
than, is the Wolfram Language complete already? In what sense? Is the Wolfram Language always complete at release time - a mere tautology.
or is Mathematica 10
the first version of Mathematica completely based on the Wolfram Language
which can be true because then the usual and due credits (to Java etc.) are given by the Wolfram Language itself. But nevertheless, it sounds great and does mean much, even if one wonders what complete means. Congratulations and hurry into the holidays before work on the first update launches!