The month of January is named for the two-faced Roman god, Janus. Am I the only one who thinks that's tragically ironic? With one of the coldest winters on record here in the Rockies, January has come to symbolize the month that chills the soul. Meanwhile, fund manager Janus (NYSE:JNS), which takes its name from the same Roman myth, has delivered chills to millions of portfolios in recent years.

That cold snap could finally be thawing. On Thursday, the Denver-based fund manager reported a 280% increase in per-share earnings for the fourth quarter, and a 65% increase on the same line for the full fiscal year.

A big boost in assets under management drove those dramatic improvements. For the year, Janus said it booked $2.3 billion in net inflows, which is fund-speak for deposits after withdrawals. More money equals more fees, and better performance leads to more deposits.

If Q4 is any indication, more checks could be in the mail. At Janus, $10.6 billion in market appreciation fattened assets under management during the quarter. Moreover, Lipper says that 70% of Janus' retail funds have outperformed their category peers over the past three and five years.

Can the run continue? I'd bet on it, especially now that there's a growth stock rally underway. What's more, Janus has a lot of fresh talent in its ranks. A good example is David Corkins, manager of the Janus Fund, which was begun by growth-investing legend Tom Bailey in 1970.

Corkins didn't beat the market in 2006 -- 10.6% vs. the S&P 500's 15.8% -- but he didn't start till Feb. 1. He's been pruning the portfolio since, adding shares of Coventry Health (NYSE:CVH) and Texas Instruments (NYSE:TXN) while taking profits in Merck (NYSE:MRK). Besides, Corkins' record was the best Janus fund investors had seen since 2003.

Still, Fools are skeptical -- the stock gets only two stars in Motley Fool CAPS. I understand that. Janus has badly burned investors before. And the shares, trading for 24 times fiscal 2007 earnings, are nowhere near cheap by historical standards.

Call it the two faces of Janus. On one hand, there's a turnaround well in hand. On the other, there's a stock that still doesn't look cheap enough to buy. Wake me when the valuation thaws.

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Fool contributor Tim Beyers, ranked 987 out of more than 20,900 players in Motley Fool CAPS, lives and works near Janus, in the cradle of the Rocky Mountains. Tim didn't own shares in any of the stocks mentioned in this story at the time of publication. Get the skinny on all of the stocks in his portfolio by checking Tim's Fool profile. Coventry is a Stock Advisor pick and Merck used to be an Income Investor pick. The Motley Fool's disclosure policy is never two-faced.