Last week we told you we expected Google's Gmail service to move from beta-tests to public launch roughly in August (which is par for the course for most Google launches.)

Turns out we were slightly wrong.

Gmail's already slowly launching beyond the initial limited betatester pool. (Which is why you're starting to see Gmail accounts show up on eBay.) Many Gmail beta testers have been told they can invite up to three friends to get accounts. Some of these friends have also been allowed to invite others (and so on and so on.)

Who gets to invite friends and when seems to be determined by an algorithm we haven't quite figured out yet. Some MarketingSherpa readers with Gmail accounts report they've only been allowed to invite friends once. Others tell us they receive frequent (in one case daily) invites to hand out to pals.

According to our own report on viral marketing (link below), three is the average number of pass-alongs folks will use even if given the opportunity to send more. So Google is actually not limiting themselves (except timewise), while cleverly giving Gmail the patina of an "exclusive" special club only a selected few can join.

You have to admire their marketing savvy. Get the most influential folks in the email universe to rush out and ask three friends to join. And then after a bit more hype builds, allow those newbies to spread influence too.

Plus, of course, Google can throttle back growth at any time by simply stopping the offers.

In the meantime, Google's spokesperson Nathan Tyler told us firmly this afternoon, "Gmail is still in beta. No date set for the official launch." In our humble opinion, this mainly means the line between "beta" and public launch is now officially grey and blurry.

Anyway, you can expect your regular MarketingSherpa issue tomorrow, but in the meantime, here are three useful links:

1. Last week's article on Gmail, including troubling news for emailers and screenshots of Gmail in action:
http://www.marketingsherpa.com/sample.cfm?contentID=271


2. Sample of the viral email invite the Gmail system sends out:
http://www.marketingsherpa.com/gmail2/ad.html

3. Proven Tactics in Viral Marketing (report mentioned above)
http://sherpastore.com/store/page.cfm/2090