Yahoo’s ranks keep fanning out all over the tech scene.

This time it is former top-ranking Yahoo exec Jeff McCombs (pictured here), who has signed on to be CFO of Tumri, an online advertising start-up.

Backed by Accel Partners and others, the Mountain View, Calif.-based Tumri is trying to crack into the online ad space with what it calls “dynamic and intelligent display advertising solutions.”

Essentially, using a product called AdPod, that means display ads that are delivered more easily and automatically with a relevant marketing message, depending on the consumer.

McCombs, 37, is a big hire for a small company like Tumri. He was SVP of Business Operations at Yahoo (YHOO).

At Tumri, he will be managing all financial activities, including financial planning and analysis, accounting, investor relations and corporate development. He will also be responsible for overseeing business development, human resources and legal.

Said Calvin Lui, Tumri president and CEO: “Jeff’s wide spectrum of experience will be instrumental in helping guide our explosive growth and will help solidify our innovation and leadership position. We are excited that Tumri’s transformative mission is attracting this high caliber of talent.”

Indeed, at Yahoo, McCombs had also served as chief of staff to former president, Sue Decker.

Previous to that, he worked at a number of investment banking, corporate development and private equity firms.

As CFO, McCombs will also be a key exec at Tumri, said Lui, helping steer its strategy.

“Making display ads performs better is the next great opportunity,” said McCombs, in an interview yesterday, noting that the sector needs to have similar ability to measure effectiveness as search ads do. “You need to be able to completely understand why one ad performs better than another online.”

Several sources inside and outside Yahoo told BoomTown that new Yahoo CEO Carol Bartz could be ready to announce a major reorganization of its management structure as early as next week, most likely on Wednesday.

While that shift could be pushed out a week or two or rolled out in pieces, Yahoo (YHOO) execs are nervously awaiting the moves by Bartz to put a new regime in place in order to more easily power through a massive reset of the troubled company.

Interestingly, many top execs are very much in the dark about what Bartz will do since she manages very close to the vest, mostly moving around Yahoo with only her longtime executive assistant in tow.

Thankfully, she also loves to write detailed memos to the staff, and she signaled the “big week” ahead in one Boomtown just obtained (see here) that was sent out today.

Those are code words for reorg, according to many sources I spoke to, coming after Bartz has spent a lot of time visiting many parts of Yahoo and conducting a whirlwind of meetings with execs.

I will be posting my Heidi-Klum-you’re-in-and-out predictions of the fate of various execs later this weekend.

But broadly, most expect Bartz to severely roll back a variety of previous reorganizations done by former CEO Jerry Yang and former President Sue Decker.

That will mean many top execs will likely be quite out–already, Decker’s chief of staff, Jeff McCombs, has quietly departed the company, several sources said–while others will be elevated.

Most sources I spoke to who have interfaced with Bartz think she will likely go with a more traditional and more accountable structure like the one she employed while rehauling Autodesk (ADSK), the computer-aided design software company she once headed, rather than the matrix-tangled Yahoo.

A change in how Yahoo makes media, which I wrote about today and was approved by Bartz, is a classic globally-centered development organization. (By the way, a significant reorg of the media organization, headed by Jeff Dossett, is also set for next week, said sources.)

Thus, most expect Bartz to do a C-level-style set-up, with execs like a COO, CTO and a new, more powerful CMO (who will also head PR), all reporting to her.

In addition, several suggested she might also junk a recent reorg that split the world into four regions. Instead, one exec could head the U.S., where most of Yahoo’s current business is, and one head international efforts.

Whatever happens, it’s clear that “Hurricane Carol”–a nickname she has been given by some employees in admiration–is getting ready to blow right through Yahoo.

Batten down the hatches–more to come…