Adobe isn't the first to institute sandboxing. 's Chrome is probably the application best known for using the technology, but 's Internet Explorer and Office 2010 also offer similar defenses. Today, Arkin again credited both Google and Microsoft for helping Adobe's developers craft Protected Mode.

Protected Mode may take some of the patching pressure off Adobe, which has had to scramble several times this year to fix flaws being used by criminals. Just two days ago, Adobe rolled out patches for a pair of vulnerabilities, one of which had been exploited for at .

Tuesday's update was the seventh this year and the sixth time in 2010 that Adobe has either issued an "out-of-band" emergency fix or moved up a regularly-scheduled patch day.

Adobe declined to lay out a timetable today for offering Reader X to existing users. A spokeswoman said only that the company would not initially roll out the new version via Reader's built-in updater.

Last month, however, Arkin told Computerworld that Adobe would urge users of the older Reader 8 to upgrade to Reader X shortly after the latter's launch, but would delay notifying Reader 9 users of the upgrade. "I would like to do both [Reader 8 and Reader 9 update notifications] within the first 12 months of X's release," he said at the time.