This past week or so has been particularly interesting for top level executives, considering that the chiefs of two of the biggest IT firms in the world have been replaced. Joe Tucci, the CEO of EMC, said today that he will no longer serve as the head of the storage giant, effective at the end of this year, confirming a story that first bubbled up this past summer.  At the end of 2012 he’ll become the chairman of the company for a period of two years, reportedly because he wants to give advice to the new CEO while he or she is still getting used to the job.

Tucci said he would do some executive chairmanship work, but minus the title because it “buys me nothing and could be confusing.” He will do things like help the sales force, identify takeover targets and be a sounding board for his successor, but he doesn’t want to hang on past his use-by date.

No successor has been officially named yet, but there are some theories on who may be in charge once Tucci departs.  Information Infrastructure head Pat Gelsinger is the most likely candidate according to some EMC insiders, but chief financial officer David Goulden, VCE president Frank Hauck, COO Howard Elias and Paul Maritz, the head of the company’s virtualization subsidiary VMware have all been brought up as well.  Gelsinger has shared with us his vision for EMC on several occasions, showing his goals for the cloud. 

Tucci’s resignation is big news, and it follows word that Hewlett-Packard has replaced its chief executive Leo Apotheker.  The company has gone through a lot of turmoil under its previous two CEOs, and eventually came to a point when (after a couple of failed investments in software) its $41 billion PC business is up for grabs.

There’s a number of industry shifts taking place concurrently, in a market that’s suffering from a bottomed-out economy.  And as technology in particular finds a fast-changing world of change and consumer demands, both EMC and HP look to the best leader to carry them through the transitions.