An Apple analyst is coming out to defend the Mac maker’s popular iPhone from a product that isn’t even on sale yet. 

That’s because the rival product, the G1 phone built by HTC and offered on carrier T-Mobile, packs a Google-owned operating system and brand. 

What’s really shaping up is a battle of rival operating systems--Google's versus Apple's--not gadgets.   

“While the G1 is a legitimate competitor with the iPhone, we believe it will have little or no impact on near-term iPhone sales,” Piper Jaffray analyst Gene Munster wrote Tuesday.

Piper Jaffray makes a market in Apple securities. 

The G1 phone sports Google’s Android open-source mobile operating system. The G1, officially unveiled Tuesday, is expected to go on sale October 22 for $179 with a two-year service contract. 

Apple's year-plus jump on the mobile market may have met its fiercest rival yet in Google. Apple's App store, which sold $30 million in applications within the first day, was quickly met by Google's investment in Android apps.

But the real distinction is that Android can be offered up for use on many devices. What remains to be seen is whether Google's Android can mate up with attractive mobile phone hardware to entice the masses and lock down the mobile advertising market.  

That strategy runs counter to Apple's tight fist approach that keeps its software tethered only to its own sleek hardware. This arrangement allows Apple CEO Steve Jobs a high level of quality control, something expected of the company's premium consumer electronics products. Yet Google will be free to expand Android widely and rapidly across countless handsets, according to Mr. Munster, giving it a strategic advantage.

That's big. Because the Google-Apple battle emerging for mobile operating systems is starting to look more and more like the Microsoft-Apple war for desktop domination. 

And everyone knows how that one played out.