The market cheered when Yahoo! (NASDAQ:YHOO) stock broke through the $31 barrier two weeks ago. 

That was the price that Microsoft (NASDAQ:MSFT) was offering when it offered to cash out the then-meandering dot-com pioneer five years ago. But it was also widely reported that Mr. Softy eventually upped its offer to as high as $33 a share in cash and stock before pulling its entire offer from the table. 

In that light, it was also refreshing to see Yahoo! smash through the $33 ceiling late last week. Why, we're even closing in on the $34.375 a share exit price that billionaire activist Carl Icahn was demanding at the time. 

Critics will rightfully argue that these milestones don't matter. The stock market has appreciated in that time. The S&P 500 has risen 23% since Microsoft's original $31 offer, so even that milestone should be adjusted to $38 -- or $49 if we go by the Nasdaq's far more impressive surge. 

Fumbling through the correct absolute or relative metric to gauge Yahoo!'s redemption or lack thereof could be a frustrating exercise. We will never agree on how high Yahoo! has to go to validate its decision for turning Microsoft away. But at least crossing $31 and now $33 offers some support for decision on a psychological level.

Perhaps more important, it's hard to kick Yahoo! when it's soaring. The stock has now more than doubled since Marissa Mayer took over last summer. Revenue growth hasn't been as kind, but improving margins and lucrative asset sales are making Yahoo! exciting again.

Despite Yahoo!'s struggles with display advertising, analysts see earnings climbing 26% this year and another 14% come 2014. This would happen despite those same pros projecting flattish top-line growth. When you factor in what Yahoo! could do to either make needle-moving acquisitions or return money to shareholders by selling more of its Asian assets, the upside is still there. 

Yahoo! isn't Google, but the investment itself has beaten both Google and Microsoft since Mayer took over.

Leaving the botched Microsoft buyout farther away in the rearview mirror with the recent rally is important. It may ultimately lead Yahoo! to move away from Microsoft as a search partner after the original deal gives the reborn dot-com darling a way out come 2015. 

Yahoo! has the momentum, and now it even has a reason.

Microsoft's typically clever Scroogled ad campaign has been bashing Google's practices at every turn. Its latest attack is on Google's new monetization scheme of inserting ads into Gmail inboxes. Well, Yahoo! just followed Gmail down that path. Does that mean that Microsoft is now attacking its Bing partner? Absolutely.

We'll see how this all plays out, but it wouldn't be a surprise to see Yahoo! try to wipe itself clean of all things Microsoft sooner rather than later.

Longtime Fool contributor Rick Munarriz has no position in any stocks mentioned. The Motley Fool recommends Google and Yahoo!. The Motley Fool owns shares of Google and Microsoft. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.