When I upgraded to ICS, I (and everyone else) lost the built-in voice dialer in Android 2.3.4. See the Vivid General forum for details on this. I tried Vlingo, and it worked okay most of the time, but it required a lot of steps. So, I tried Cyberon Voice Commander and was pleased with how well it worked and how closely it matched the original voice dialer when connected to my car's audio system via bluetooth. See my post for more details.
http://xdaforums.com/showthread.php?p=24400306#post24400306
There may be other apps that work, so I am not saying this is the only one.
http://xdaforums.com/showthread.php?p=24400306#post24400306
There may be other apps that work, so I am not saying this is the only one.