Jon Rubinstein, the former CEO of Palm, has left his role at HP. Rubinstein joined the hardware giant as part of its July 2010 acquisition of the smartphone pioneer.  Since then, HP has struggled in the mobile devices business, subsequently recording more in costs and goodwill writedowns related to the wind-down of the unit than it paid for Palm in the first place.

In an interview with The Verge, Rubinstein said that he had intended moving on since before the launch of the TouchPad tablet in the middle of last year, but that he was asked to “stick around and help them with the webOS transition.” The company announced plans to offer webOS on an open source basis late last year, and has subsequently updated on its progress to this end.

It was noted that in the 19 months the webOS business has been under HP’s guidance, the parent has had four CEOs – including one who announced the decision not to offer any more hardware using the platform. When Palm was acquired, Mark Hurd was CEO, who was followed by Cathie Lesjak on an interim basis, Leo Apotheker and Meg Whitman.

When asked whether HP had made the right decision in open-sourcing webOS, Rubinstein countered “versus what?” He told All Things D: “well, if HP invests in it the way it says it’s going to and they can build a community around it — and that’s not just people developing for the platform, but other companies using it — it will do well.”

Last year it was announced that Rubinstein had taken up a “product innovation role” within HP’s personal systems group, as part of a restructure of the webOS business.