Shantanu Narayen – the President and CEO, Adobe Systems was recently quoted as saying:
"We are on track to deliver a new version of Acrobat late in our fourth quarter that will focus on enabling knowledge workers and enterprises to collaborate across critical document workflows." [NOTE: Adobe's fiscal fourth quarter ends in late November 2010.]
So it appears that there's a really good chance that Adobe Acrobat 10 (or Acrobat X) will be shipping by mid-October to late-November in 2010.