Looks similar to http://graylog2.org/
Graylog2, though, had problems with it's original implementation based on capped containers in MongoDB. It has since moved to ElasticSearch.
There are both gelf inputs and outputs for Logstash so you can send your logs to Logstash as if they were going to Graylog2 and do additional munging and still send them out to Graylog2 from there.
I was planning to setup Logstash next week so your input would really help. Thanks!
The Graylog2 web interface is pretty awesome and it has some neat stuff built in. Logstash ships with a fairly spartan web interface though we're going to replace it with a ruby port of Kibana in the future.
Logstash can accept data from GELF senders (via the gelf input plugin I wrote) or send to gelf receivers (like Graylog2).
Graylog2 is awesome, don't get me wrong. I just had to bail on it when it was still on MongoDB because I couldn't justify the cost of instances needed to get a MongoDB instance that could hold more than 4 hours of data.