Following up on this morning’s “just the facts” post about Google’s AdMob acquisition, here’s a bit more commentary.

First off, this is a big deal — both in size and in what it could mean for the two companies. Google is clearly keen on replicating its online dominance to the mobile world as growing smartphone penetration drives the growth of the mobile Web. What it’s done so far has mostly been text advertising on Google searches and throughout its AdSense for mobile network — mirroring its online strategy.

What AdMob brings is an extensive network of display ad inventory on 15,000 mobile Web sites and applications for iPhone and Android. It’s been the largest ad network for in-app ad inventory on the iPhone, which has important implications for demographic targeting and audience segmentation. With AdMob, Google can now reach incremental mobile users and beef up its ability to serve mobile display advertising.

This is a strong position if you combine it with the fact that Google has so many existing online advertisers. It can transition many into mobile marketing with a one-stop-shop approach. This has implications for many more advertisers entering AdMob’s network. Otherwise Ad networks rely on a combination of direct sales and some self service. So in that respect, Google’s front door to advertisers gives AdMob an advantage over other ad networks.

Self-service mobile advertising will grow, which suggests Google is well positioned. We could see more and more mobile distribution options integrate with its existing AdWords dashboard. Other mobile ad networks have meanwhile begun to add self-service tools to reach more mid-market and SMB (long tail) advertisers — Jumptap most notably. This will be a growing source of ad revenues as mobile marketing reaches these segments of the market, just like they did online.

Meanwhile, many of Admob’s competitors in the mobile ad network world, have been quick to comment on the deal. Below are e-mailed comments from Jumptap and Millennial:

Paran Johar, CMO Jumptap

“The announcement is causing tremendous excitement as it validates the enormous potential of mobile advertising. We predicted consolidation in the industry and Admob’s broad high volume business model is highly synergistic for Google. The industry front runner will be determined by who can deliver the most advanced targeting capabilities for better ROI for advertisers and publishers.”

Paul Palmieri, President and CEO, Millennial Media

“What happened today is astounding. Google’s perspective has always been that mobile is just the internet. Today Google validated what many companies to include Millennial have thought for years — that mobile is a different market with a huge potential for advertising; possibly a bigger opportunity than online media. As the clear leader in mobile brand advertising, we are happy to see a player like Google bring economies of scale to the performance advertising space in mobile. Millennial Media has generated our substantial lead in the market by focusing on the advertiser, delivering results, and has been rewarded with the largest reach of any media company large or small. Reaching 80% of the US mobile audience, we look forward to working alongside the Google/AdMob pairing to fully realize the vast potential of the mobile advertising market. Congratulations to Google and to AdMob.”