Add staleness and clients/exporters

content/docs/introduction/roadmap.md

@@ -72,6 +72,18 @@ other long-term storage backends.
 
 GitHub issue: [#10](https://github.com/prometheus/prometheus/issues/10)
 
+**Improved staleness handling**
+
+Currently Prometheus omits time series from query results if the timestamp for
+which the query is executed is more than 5 minutes away from the nearest
+sample. This means that time series will grow "stale" in instant queries after
+not receiving samples for 5 minutes. This currently prevents usage of
+client-side timestamps from the Pushgateway or CloudWatch Exporter, which might
+indicate a time more than 5 minutes in the past. We plan on only considering a
+time series stale if it was not present in the most recent scrape.
+
+GitHub issue: [#398](https://github.com/prometheus/prometheus/issues/398)
+
 **Server-side metric metadata support**
 
 At this time, metric types and other metadata are only used in the client
@@ -80,3 +92,11 @@ Prometheus server. We plan on making use of this metadata in the future. For
 example, we could suggest automatic rates over counters, warn users if they
 take the rate of a gauge, or display metric documentation strings. The details
 of this are still to be determined.
+
+**More client libraries and exporters**
+
+Prometheus has a range of client libraries and exporters. There are always
+more languages that could be supported, or systems that it would be useful to
+export metrics from such as Python or Collectd. We will add more as we need
+them. We are also happy to accept pull requests and advise on how best to
+integrate with Prometheus.