Earlier this year, as Microsoft executives continued to lust publicly for a Yahoo search agreement, I started to wonder why the Redmond company wasn't turning its attention to Twitter instead.

Sure, a Yahoo deal would immediately give Microsoft 20 more points of market share. But when you really start to think about Twitter, the whole Yahoo thing starts to seem like Microsoft looking for incremental growth in the market of today, while neglecting the market of the future. If it continues to grow, Twitter promises something highly interesting to search -- an immense database of public thoughts.

Which is why there should be alarm bells going off in Redmond tonight. Michael Arrington of TechCrunch, citing anonymous sources, reports that Google is in talks to acquire Twitter.

Depending on which of his sources is right (assuming at least one of them is) the talks are either in late or early stages. Whatever the case, it will be fascinating to see if Microsoft tries to cut in.

The situation could become reminiscent of Google's acquisition of online advertising company DoubleClick, which forced Microsoft to catch up through its record $6 billion purchase aQuantive. If Google/Twitter happens, however, there doesn't seem to be a natural way for Microsoft to respond -- unless it's able to somehow pull off a Facebook deal.

In one sign of Twitter's increasingly pivotal role, the popular microblogging service was mentioned no fewer than half a dozen times by panelists and attendees at panel discussion about online travel in Seattle tonight.

Even if Microsoft loses out to Google, at least one Seattle techie could benefit. Amazon.com founder Jeff Bezos invested in Twitter last June, participating in what was reported at the time to be a $15 million venture round.

At the time, PaidContent placed the valuation of Twitter at less than $100 million. But Twitter went on to raise more than $35 million from Benchmark Capital, IVP and others in February at a reported valuation of more than $250 million. And the Twitter user base has grown since then as it has gained momentum and become a bigger part of the cultire.

Based on tonight's news, however, it looks like Twitter's value may ultimately be determined by how much Google is willing to pay -- or by how much higher Microsoft is willing to go.

Update, Friday morning: AllThingsD's Kara Swisher is refuting Arrington's report.

John Cook contributed to this post.