Online shopping traffic certainly increased on Monday over the previous Friday, according to sources directly involved in generating that traffic, though surveys show shoppers may not be spenders.

UPDATE 7:15 pm ET November 29, 2006: This afternoon, comScore Networks made it official: Cyber Monday lives! US online retail holiday spending last Monday was 26% higher than for the Monday after Thanksgiving 2005, totalling $608 million versus $484 million. Earlier, comScore had predicted US online consumers could spend as much as $2.74 billion this week alone, and it looks now like we're well on our way to achieving that figure.

CORRECTION 3:45 pm November 29, 2006: This afternoon, a Microsoft spokesperson corrected the figures we received this morning concerning traffic increases for MSN Shopping. "The 21 percent increase is for the entire weekend (Black Friday through Cyber Monday), not just Black Friday," the spokesperson told BetaNews.

As the first sales figures from online shopping traffic last Monday are being compiled, retail and technology analysts this morning are poring over the data like conspiracy theorists examining fresh sighting photographs of Santa Claus’ sleigh under a microscope: They’re seeing what they want to see.

As a result, “Cyber Monday” is either a boom or a bust, depending on whom you ask.

Microsoft reported this morning that its MSN Shopping service received 21% more visits on the day after last Thanksgiving than for the same period in 2005, but 63% more traffic last Monday than in 2005, and at the same time doubling its traffic from “Black Friday 2006.” While this sounds impressive on the surface, we worked this out as an algebra problem, and discovered that in order for these facts to be correct, MSN Shopping’s Black Friday of 2005 must have had 48% more traffic than its Cyber Monday 2005.

In other words, if Microsoft’s figures prove Cyber Monday exists this year, it disproves its existence for last year.

Meanwhile, PriceGrabber.com -– which operates a referral service for multiple online retailers, often under different brands –- reported late yesterday that its referral traffic for last Monday was 15% higher than for the previous Friday, and 45% higher referral traffic for the entire month of November thus far over 2005.

On the debunking side of the spectrum, financial analysts Deloitte & Touche USA this morning declared “eFriday” the biggest online shopping day of the year thus far, pronouncing that in its survey of 1,101 adult shoppers, 20% of those responding say they shopped online last Friday, while 19% say they shopped on Monday. Almost half (47%) of those who shopped on Friday say they also shopped in traditional retail stores the same day. So that’s the ballgame as Deloitte sees it: Friday wins over Monday by one point.

The small print, however, reads the poll’s margin of error is plus or minus 3%. (Just to be on the safe side, we recalculated Deloitte’s margin of error, finding it to be 2.953%.)

Corporate Web services provider Akamai, which provides Internet infrastructure to hundreds of major online merchants, verifies this morning that Monday’s peak isn’t just the base of a bigger upswing to come, at least not for this particular week. Akamai’s figures today show that, at the peak traffic periods for the retail sites its tracks, Tuesday’s traffic peaked at 376,962 unique customers per minute fewer than for Monday.

Analysts cite sales data from previous years in pointing out that online shopping days in mid-December can actually pull in higher traffic than for the Monday after Thanksgiving. Many cite the period in-between December 15 and 19. But this year, that critical period straddles a weekend, certainly knocking out Sunday and probably Saturday as well.

What does it matter whether a particular Monday is a bigger shopping day than a given Friday, or vice versa? It’s actually a critical issue for online retailers as they comprise a larger segment of the global economy. In traditional retailing, it’s always been easy for merchants to plan their after-Thanksgiving sales. Since the following Friday has been a traditional shopping bonanza for decades, their strategies have centered around how early they should open, and what kinds of doorbuster bargains they should have ready for the first shoppers through the turnstile.

For online merchants, it’s not so easy. Timing is just as critical for online merchants planning a sale or bargain day. But they have to think simultaneously like retailers and like TV program planners: They have to plan their sales when their “audience” (i.e., their consumers) is available. If they’re out shopping, they’re not on their computer.

With consumer sentiment in the US unexpectedly declining, and Federal Reserve Chairman Ben Bernanke warning yesterday of continued moderation in the US economy – including slower housing starts – there’s still some rational concerns over whether all these online holiday shoppers are actually spenders. More data is expected from Web traffic analysts comScore Networks later today.