Google's latest earnings conference call was special. This time--one-time only, not to be repeated in the coming quarters--executives promised to offer some financial results on Google's most important emerging growth businesses.

Google's leaders chose to highlight powerful results in its display advertising, YouTube advertising, and mobile advertising segments. They chose not to say anything about Google's enterprise apps business.

Why not? I don't know. But every time Google passes on such an opportunity, it misses a chance to assure CIOs that Google is every bit as committed to enterprise apps as the IT execs who bet their careers and businesses on implementing Google Apps in their companies.

The businesses Google execs did highlight share a common thread--a billion, with a B:

$2.5 billion: That's the annual revenue run rate for Google's display advertising, meaning banner, branding kind of ads, as opposed to the search-related text ads that are Google's core.

2 billion: That's the number of YouTube views per week that Google's now getting paid for.

$1 billion: That's the annual revenue run rate for Google's mobile advertising.

"All these businesses are growing," said Jonathan Rosenberg, senior VP of product management. "I hope this gives you a sense of why we're so excited about the incredible emerging businesses at Google." (A replay of the call is here. )

So is enterprise apps anywhere near that magical $1 billion annual revenue mark? Here's what the financial statements say.

Enterprise app subscriptions fall under Google's "Other" line on the financial statement. That Other line is booming--up 35% year over year, faster growth than Google revenue overall (which was up 23%). And that Other line is past the $1 billion-a-year revenue run rate: $254 million for this quarter. Yes, that's a pittance compared to Google's $7.3 billion total revenue for the quarter, but $1 billion was enough to be excited about mobile search, since it's a vital to the future of the company.

Of course we don't know how much of that Other line is enterprise apps. The only thing we learn about that number in the conference call is that it used to include Google's direct sales of the Nexus One phone; dropping that product led to a slight dip in quarter-over-quarter Other revenue. So, maybe enterprise apps is still just too small a business to make the cut. Or maybe it's not growing fast enough, or not profitable enough. Maybe it's no more complicated than that.

Google has every reason to tout it enterprise apps business, if it's thriving. Every other emerging revenue source it talked about focused on advertising. If it had anything close to a $1 billion-a-year business that wasn't based on advertising, that helped diversify a company that's constantly labeled a one-trick pony, shouldn't Google leaders be excited about it?