In addition, the update allows you to create rules to filter users that are in or missing from your contacts list. It's sort of a follow-up to the change that Google made in February, when it added your Google+ Circles (you are in Google+, aren't you?) to Google Voice.
In this case, however, Google added the features because end users have been clamoring for them for some time.
They are nice additions to Google Voice functionality, but Google Voice is still missing a big feature that it should support if it wants to replace standard cellular phone service, which is the way that Google seems to be positioning it. That feature is MMS.
Let's be honest: Google Voice hasn't exactly seen tons of features added since Google acquired GrandCentral back in 2007. True, it's been added to Android and iOS, and seen numerous changes, but we're still missing what many would call core functionality after all this time.