Here's an idea for a quick-and-dirty enhancement to existing applications: Rather than disable IDNA entirely (which is quick but too dirty), or flag all IDNs (almost as quick but still too dirty), just flag all IDNs in .com and .net. This would be significantly less damaging to IDN deployment (which could proceed unhindered in the other TLDs, particularly the ccTLDs), but is still extremely simple and could be rolled out immediately while more sophisticated heuristics are developed.
AMC
