Good new for discretionary traders... http://www.hedgeworld.com/open_news/read_newsletter_aa.cgi?section=legl&story=legl3368.html
Looks like a non-event to 'common' folks. The 500ms minimum order lifetime would have had an impact (for the better or the worse), but that is apparently off the table.
The beginning of the end for HFQ (High Frequency Quoting). Something like it will likely be implemented in the US soon as well. What is perhaps not thought through is, this will increase volatility, not decrease it.
RE : volatility, one can argue that HFT reduces volatility in normal times but during periods of extreme market stress it may increase volatility. To use Taleb's language it's something that gives the appearance of orderly markets but in fact makes the system more fragile. But I am not sure of his opinion on HFT.