Former Palm CEO Jon Rubinstein has left Hewlett-Packard effective today. No reason was given for his departure although it seems that both parties split on good terms, as first reported by All Things D.

Rubinstein has reportedly completed his mandatory 12-24 month stay at HP after the Palm acquisition in 2010. HP spokesperson Mylene Mangalindan publically stated that Rubinstein had fullilled his commitment to HP and that they wished him well. In a brief comment to All Things D, Rubinstein said that he planned to take a well deserved break after working to develop webOS for four and a half years.

Rubinstein is perhaps best known for his time at Apple where he helped develop the iPod. He eventually left Cupertino in 2006 to join Roger McNamee in the private equity firm Elevation Partners after they invested in Palm in 2007. Rubinstein took over as CEO of Palm in 2009 and led a vast restructuring of the company's product lines.

WebOS replaced PalmOS on new handsets like the Pre, Pixi and Veer. Once HP acquired Palm, WebOS was used one last time on the HP TouchPad briefly before it was discontinued after only a couple of months on the market. The OS has since been made available as an open source project for HP.

All Things D notes that once the decision was made for HP to abandon WebOS, it was only a matter of time before Rubinstein left. Sources with close ties to Rubinstein noted he hadn't been seen at HP's offices after the decision and that his new assignment on the product innovation team within HP's personal systems group was a stepping stone to his departure designed to reduce PR backlash.