Microsoft stunned the online business world (actually the entire business world) today with the news that it has made a $44.6 billion bid to buy rival Yahoo — the largest such bid ever placed by Microsoft.

Microsoft reportedly chose to make an unsolicited bid — the polite term for takeover — as opposed to engaging in more friendly deal negotiations for the sake of speed, claiming that such negotiations would be protracted and would receive a huge amount of public scrutiny.

Yet, the heads of the two organizations have reportedly already engaged in a friendly conversation about the possible deal. According to today’s New York Times, “Steven A. Ballmer, the Microsoft chief executive, said that he called his Yahoo counterpart, Jerry Yang, on Thursday night to tell him that Microsoft intended to bid on the company, and that they had a substantive discussion. ‘I wouldn’t call it a courtesy call,’ he said in an interview.”

The possible merger is being talked about as a way for the two companies to keep up with super-rival Google, which has outpaced its competition at a dizzying rate in recent years — in a market that’s expected to “almost double to $80 billion by 2010″, according to Bloomberg.com. (The same story also reports that Google announced a “52 percent increase in fourth- quarter sales growth” yesterday, “its 14th straight quarter exceeding 50 percent.”)

But will the bid turn into a sale? Yahoo isn’t expected to put up much resistance (particularly in light of its recent underperformance). And both companies are suffering from slipping stock prices and well-publicized internal troubles. Yet a merger of this size has built-in difficulties when it comes to getting the necessary regulatory approval. “Besides the question of Yahoo’s acceptance, Microsoft’s bid also faces regulatory scrutiny in Washington and Europe. On Friday, the Justice Department said it is ‘interested’ in reviewing antitrust issues. European Union officials declined to comment,” reports the San Diego Union-Tribune.

Many observers feel the companies will have a harder time gaining approval from the EU than from Washington. Ultimately, that may even be part of the plan, since bids such as this are sometimes made for publicity reasons. “[I]t’s always possible with Microsoft that this Yahoo deal was never meant to be finalized,” suggests MarketWatch’s John Dvorak. “This happened with the Microsoft attempt to buy Intuit some years back. It may be a ploy to steal Yahoo technology or key employees.”

Count us as among those eager to see how this story unfolds. Stay tuned to the Aplus.Net Blog for more details.