We will publish a paper at IEEE P2P'11. In the paper, we describe how we manage to achieve median lookup latencies between 100 and 200 ms and less than half second in 98% of lookups in Mainline DHT.
We also measure uTorrent's performance and we found it surprisingly good, with a median latency well under one second.
We have developed a complete implementation of BEP5 and made backward-compatible modifications to routing and lookup algorithms. We also built a toolkit which analyzes Mainline DHT traffic, so any node implementation can be measured without instrumentation.