Microsoft-Yahoo coming back to life?

As Yahoo’s stock dives, speculation is rising that Microsoft could make another acquisition bid.

In May, at the height of negotiations, Microsoft offered Yahoo $33 per share — a significant premium, but still a price that Yahoo execs said undervalued the company. Now, with Yahoo stock hovering around the $13 mark, the Associated Press says Yahoo would be under even more pressure to accept a new Microsoft bid.

Most of the talk around a Microsoft-Yahoo deal focuses on Yahoo’s finances. But there’s an equally important part: what the acquisition would mean for Microsoft’s search and advertising business. That’s an area that, according to at least one Microsoft partner, needs some serious improvement.

John Powers, CEO of Digipede Technologies in Oakland, Calif., announced today that his company is done using Microsoft’s online advertising system, AdCenter.

“Microsoft AdCenter is entirely without value to our company, inferior in every measurable way to competing offerings from Google and even Yahoo, and a time-and-money sink of unusual scope, even for Microsoft,” he wrote on his blog, Powers Unfiltered.

Microsoft has poured a lot of money into AdCenter improvements over the past few years, but Powers said none of them have helped drive qualified leads to his business. He also said AdCenter’s interface is clumsy, and the billing system is “apparently defective.”

In discussing the potential of a Microsoft-Yahoo deal, the AP raises the most important question of all: Is Microsoft still interested?

We don’t know yet. But from the sound of things, they should be.