Sole grinds is one.  I believe they also redesigned the grooves for more spin but also to remain legal.

Ritch, 

The grooves will offer more spin, with there aggressive groove edges and 100% inspected tight tolerance that are pushed to the limits allowed by the Rules of Golf.  We also heat treated the face of the SM4 wedges for more durable grooves.  We have also added extra milled micro edges that allow for partial shot control.

Cameron

1-888-TITLEIST 

Thank you.  I was impressed with the performance of a second hand Vokey wedge I picked up as a replacement for a wedge that had been stolen.  I have lately been thinking of converting all the wedges to Vokeys.

You can't go wrong with a Vokey (my first ever was a 258-12 in 2007-2009 and it was my universal short game club).   What I did before buying a new SM3 50-08 was get a 2nd hand SM2 50-08 and playing a couple rounds of golf with it bent to 51 and lie to 64.5*.   I returned it to the store and bought the new one after finding out I really loved it.  I also upgraded from an SM2 60-07 and 64-07 to SM3 62-07 (I played the former two for almost 2 years).   I've been using my SM3 54-11 for over a year now and the 62-07 for 9 months.  I've had the 50-08 and 58-04 for 6 months now.  I've had some great golf shots with all my Vokeys.

What are SM3s? Do you mean the SM2 C-C?

SM2 is the Spin Milled 2nd generation (the ones sold up to 2010)

SM3 is another name for Spin Milled c-c (at least that is my understanding from what I read here).