The latest release of NEST (NEXT ESA SAR Toolbox) 5.1 is available for free on the NEST website.

This update adds InSAR optimised coregistration, integrated phase unwrapping, and support for ERS/Envisat cross interferometry.
For working with large Sentinel-1 data, a computer with at least 8GB RAM is recommended.

This may likely be the last update to NEST before its major evolution with the Sentinel-1 Toolbox, to be released in September 2014.