Simon Beresford-Wylie, head honcho at infrastructure giant Nokia Siemens Networks, will step down at the end of September, to be replaced by Rajeev Suri, who currently leads the services business at NSN.

Beresford-Wylie is credited with being one of the leading drivers behind the creation of Nokia Siemens Networks and assumed the position of CEO of the company when it commenced operations on April 1, 2007.

Simon Beresford-Wylie is profiled in telecoms.com’s 40 mobile industry leaders to watch

He will support Suri during a transition period through November 1, 2009 before leaving the company. Beresford-Wylie will also leave the Nokia group executive board on September 30.  He has not yet revealed whether he has taken another job in the industry.

In other news, the firm’s parent and handset market leader Nokia has unveiled the N97 mini, a version of the flagship N97 that, as the name suggests, is pretty much the same as the original N97 in a smaller form factor. It costs €450 before subsidies.

The N97 will be used to debut Nokia’s latest push into the social networking via a deal with Facebook. Lifecasting with Ovi allows users to publish their location and status updates directly to their Facebook account from the home screen of a mobile device.

Also leaving the Nokia stable this week is the X6 music phone with 32GB of on board memory and a 3.2″ touchscreen and the X3 music phone, a lower end Symbian Series 40 device.  The X6 has an estimated retail price of €450, with the X3 retailing for an estimated € 115. Both devices will ship during the fourth quarter of 2009.