Sentry is a realtime event logging and aggregation platform. It specializes in monitoring errors and extracting all the information needed to do a proper post-mortem without any of the hassle of the standard user feedback loop.
Sentry is a Server
The Sentry package, at its core, is just a simple server and web UI. It will handle authentication clients (such as Raven) and all of the logic behind storage and aggregation.
That said, Sentry is not limited to Python. The primary implementation is in Python, but it contains a full API for sending events from any language, in any application.