It's not the pipeline itself that's interesting but who owns it and who doesn't.
Russia has struck a deal with Kazakhstan and Turkmenistan for a pipeline to carry natural gas from the Caspian Sea to Russia. The deal puts an end to a Western bid intended to route the pipeline under the Caspian so that it wouldn't have to go through Russia.
The pipeline agreement increases Europe's dependence upon Russia for natural gas supplies, leaving the EU more vulnerable to potentially having a significant part of its fuel supply cut off at Russia's whim. Russia has already shown its willingness to use its energy exports to political advantage with countries like the Ukraine.