Financial analysts at Piper Jaffray believe Apple's iOS is delivering "the biggest or close to the biggest portion" of Google's mobile search revenue. The report is ironic given that IDC expects Google's own Android platform to capture a 61 percent share of the global smartphone market this year.

"Assuming [Apple's] iOS generates around 40 percent of total mobile search revenue" for the search engine giant, "iOS would generate about 2 percent of Google's net revenue in 2012," Piper Jaffray analysts Gene Munster and Douglas Clinton said Wednesday.

Though Munster and Clinton say it appears increasingly likely that Apple will replace Google Maps with its own mapping app, they do not expect Apple's rival offering to significantly impact the search engine giant given that Google Maps could still be delivered to mobile devices running iOS.

"We believe it is possible that Maps as its own application in the App Store could be more popular than any of Google's other applications," Munster and Clinton said.

Pushing Chrome to iOS

Replacing Google Maps represents a risk for Apple because the highly popular service is reportedly used by more than 1 billion people each day. Moreover, Apple will find it extremely difficult to launch a mapping application that is immediately competitive with Google Maps, which went live in 2005 and has been accumulating a steady stream of innovative features since.

For example, Google said Wednesday that it was beginning to add 3-D models for entire metropolitan areas to its Google Earth offering for mobile devices. "By the end of the year we aim to have 3-D coverage for metropolitan areas with a combined population of 300 million people," Google Maps Vice President of Engineering Brian McClendon said in a blog post.

Beyond Google Maps, Munster and Clinton also expect the search engine giant to continue to introduce other new mobile offerings in the iTunes App Store alongside currently available apps such as Google Search, Gmail, Google+, Google Translate and Google Earth.

"We believe Google will be more aggressive with offerings in the App Store," Munster and Clinton said. "Beyond Maps, we believe Google may make a significant push with Chrome on iOS this year."

Earlier this year Google introduced Chrome for Android, which exemplifies the kind of simplicity that Google is aiming for in the mobile environment, said Google CEO Larry Page. "All of your tabs are there across your desktop and Android, you can even click the back button on a different device and it just works," Page told investors during a conference call in April.

Doubling Down on Siri

Mobile is quickly becoming a backbone of many clients' overall advertising strategies and "has huge headroom to grow," said Google Chief Business Officer Nikesh Arora. Google's clients and partners are also increasingly looking "for complete solutions that work across all screens: desktop, mobile, tablet and, in the future, television," Arora told investors.

Google's first-quarter operating profit was $3.9 billion, with its operating margin slightly above 37 percent.

"These robust margins give us the confidence to continue to fully fund the strategic growth areas such as mobile, Android, YouTube and Chrome," said Google Chief Financial Officer Patrick Pichette.

Piper Jaffray views Apple's launch of Siri on the iPhone 4S as "a soft shot" at Google's presence on iOS. "On Apple's side, we believe the company, as Tim Cook noted, is 'doubling down' on Siri," Munster and Clinton said. "We expect Apple to continue to innovate around discovery on iOS through Siri and push traffic to services other than Google."