It hasn't been long since the Android 4.3 update was released to fix the second-gen Nexus 7's multitouch glitches. However, a number of users have complained that the update hasn't done much to actually fix anything.
Android Police reports that although there were plenty of positive comments about the JSS15Q update--the one specifically mentioned by Paul Wilcox in the Google Product Support forums--the real problem with the Nexus 7's multitouch issues may actually be hardware related. One user posted a link to the update history for the touchscreen driver in the forums, with evidence suggesting that the digitizer inside the Nexus 7 doesn't have the best track record. The history documents about 18 different instances of ghost touches, wrong gesture detection, and improper calibration. That means that some tablets have either been badly calibrated or have grounding issues, but only the former can be fixed with a software update.
Android Police iterates that most of these issues are merely speculative and based on anecdotal evidence. Wilcox has left a comment in the forums stating that Google has been made aware that the recent update hasn't completely remedies the touchscreen problems, but for now they're just looking into it.