With the clock ticking on tomorrow's unveiling of the Nexus One, it seems most of the focus has been on the hardware and plan details (see below). But looking at the Nexus One as just another Android phone that Google happens to sell is to miss its potential significance as a hardware platform for Google's increasingly popular software offerings. Specifically, the Nexus One could have big implications for Google Voice and Google Apps.

One of the ways that a Google-branded phone makes the most sense is as a platform for the company to expand the functionality and user base of Google Voice. With the Nexus One launch, we may see Google Voice open up to more users, and we might also see the introduction of long-awaited number portability to the service.

Right now, Google Voice is invitation-only, but that could change after the launch of the Nexus One. Google will likely want Voice to be the primary way for Nexus One users to place calls on the handset, and that would mean giving out a Google Voice number to everyone who buys a Nexus One and who doesn't already have a Google Voice account. Such a move would lay the groundwork for a future Google Voice transition from regular voice connections (where the Google Voice app makes the connection in the background using the network's voice side) to SIP over the network's data side, enabling Google to bill customers directly for VoIP services. But given network bandwidth issues, such a combination of the newly acquired Gizmo5 SIP network and Google Voice will probably either not launch with the Nexus One, or it will be available only via Wi-Fi.

Once Google is finished rolling Gizmo5 into Google Voice, the resulting product on Nexus One will raise Google's profile as a carrier- and network-independent provider of IP-based telephony services (voice, voicemail, SMS, directory services, etc.).

With rumored support for up to five phones per Google Account, it's not clear how Google Voice will handle multiple phones per user—will we get multiple Google Voice numbers that point to the same account (sort of like having multiple e-mail aliases pointing to one inbox), or will we get multiple Google Voice accounts? Or will we get to choose between the two options on a phone-by-phone basis?

The other question raised by Google Voice on Nexus One concerns number porting. Google hasn't enabled the public to port their existing numbers to Google Voice yet, but letting Nexus One buyers port numbers to Voice (as opposed to just porting them to T-Mobile) would seem logical. We'll find out tomorrow morning if Google will let us port existing numbers to Google Voice for use on the Nexus One.

Nexus One for My Domain?

The other issue that's worth thinking about is the Nexus One's possible relationship to Google's business offerings—specifically Google Apps for My Domain. It seems likely that businesses that use Google Apps will at some point be able to purchase and administer the new phones centrally, with the phones and plans tied to the domain owner's account. In other words, as a Google Apps customer, I should be able to buy a Nexus One for each employee account on my domain, complete with a Google Voice number. That way, I can cheaply and easily equip a workforce with centrally billed and managed mobile calendaring, IP telephony, messaging, contacts, etc.

I'd be surprised if Google launches the Nexus One with this kind of Apps-based enterprise focus, but it does seem like the kind of thing it would add eventually. And when it launches, it would be a low-cost alternative to RIM's Enterprise offerings.