We’ve wrote recently of Google’s latest free spreadsheet offering, and the number of other competitors out there.

Now Socialtext, the early Palo Alto wiki company, tells us it has acquired wikiCalc, a spreadsheet product produced by Dan Bricklin. Bricklin carries weight because he invented the first spreadsheet, VisiCalc. The difference, compared to Google, will be that this wikiCalc product is open source, and will give users ways to develop and change the product to fit their own needs, according to Socialtext chief executive, Ross Mayfield.

The move is significant on several fronts. Users of Socialtext’s wikis will soon be able to edit spreadsheets from within the wiki. And because wikis can be shared with others, this gives users the same shared experience that Google is offering.

When Ross told us about the deal a few days ago, we also asked whether there is anything Socialtext and WikiCalc combined will be able to do functionally that Google’s product can’t. He said he’d back to us with more detail, saying he hasn’t kicked around the Google product enough to know. For one, he said the combined product will be run both offline and online, and from the Mac, Windows or Linux.

Bricklin started work on wikiCalc almost a year ago; the terms of the deal were not disclosed. The beta version of wikiCalc will be released tomorrow (see here).

WikiCalc is an open source product, and Bricklin has garnered quite a bit of feedback. However, he has remained the sole “contributor,” and thus Bricklin and SocialText are free to develop this as a commercial product and license it to others, Mayfield told us.

Socialtext also wants to sell this to big companies, which require more secure features than a pure Web-based product like Google’s offers. In WikiCalc, every spreadsheet cell change is recorded in a log, essential for regulatory/Sarbanes Oxley compliance, Mayfield said. So there are fewer competitors in this space. Microsoft will soon offer more sharing capabilities, but will likely remain more expensive.