The update to version 4.06.651.9 went live sometime this morning, and is available for customers to manually retrieve via their device settings. The listed changelog simply says "System stability improvements," so we don't imagine there are any user-facing changes or issues to contend with.
The update will push to all customers starting March 24, but as mentioned a quick trip through Settings > System updates > HTC Software update should get you hooked up today.
Source: Sprint. Thanks everyone who sent this in!