Labor Day is behind us and the summer is over, but for Yahoo and Microsoft, Rumor Season may just be getting started … again.

Yesterday, both the New York Times’ DealBook blog and TheStreet.com speculated that a Microsoft acquisition of Yahoo, in an effort to take on mutual foe Google, might not be such a far-fetched idea after all, citing the release of a report by Bear Stearns analyst Robert Peck.

According to DealBook, Peck writes in his report that Yahoo makes “an attractive acquisition candidate for either traditional media companies […] or for technology companies such as Microsoft.”

In the same post, however, DealBook blogger Andrew Ross Sorkin writes:

But neither Microsoft nor Yahoo has ever publicly acknowledged any takeover talks. The closest either one came to doing so was last year, when Mr. Semel, Yahoo’s chief executive at the time, said that his company had tossed around the notion of Microsoft buying a stake in its search business. But he quickly added that he found such a transaction deeply unpalatable, saying it “doesn’t make any sense.”

Similar rumblings of a potential Yahoo-Microsoft deal made the blogosphere rounds last spring, but dropped out of sight by Memorial Day. Despite Peck’s note to the contrary, it looks like it should have stayed out of sight. I’d say we can put this rumor to bed now, if not permanently, then at least for the next six to twelve months.

At least that’s what Google’s hoping for.