I believe it is fairly irrelevant.
Firstly, every domain (for example Web, OS X, iPhone, Windows) has its own aesthetics which means experience from gadgets won't necessarily transfer that well, in the same way a great Windows UI won't necessarily be a great OS X interface.
And owning a gadget hardly ever teaches about the underlying hardware or software implementation.
However, being able to appreciate great design, whereever it appears, whether that is in gadgets, literature or architecture has to be useful. And a curiosity about the world and a determination for life to be better will probably often lead to great programmers getting gadgets, however this is a case or correlation not being the same as causation. The gadgets don't help the programming skills, but the same traits drive both.