Grafana's stable release of version 4.0 marks a significant upgrade, introducing numerous minor features, fixes, and user experience enhancements, with the standout addition being the alerting feature. This new alerting capability transforms Grafana from a mere visualization tool into a critical monitoring solution by allowing users to configure alert rules using existing graphs, set threshold levels, and receive notifications through multiple channels like Slack, PagerDuty, and Email. The release supports data sources such as Graphite, Prometheus, InfluxDB, and OpenTSDB, with Elasticsearch in development. Additional features include an alert list panel, ad-hoc filters for dynamic key/value filtering, and several UX improvements like TV and kiosk modes for streamlined display on wall-mounted screens. Grafana v4 also introduces enhanced dashboard building experiences, new keyboard shortcuts, and maintains backward compatibility, ensuring old dashboards continue to function seamlessly while encouraging users to update plugins to ensure compatibility with the new version.