GDrive, Google's long-rumored online storage service, remains unannounced and unacknowledged by the company. Yet sightings of the service, which seems destined to become the foundation of the company's Chrome OS, not to mention Google Docs and Google App Engine, continue.

Originally called "Platypus," GDrive has become the tech industry's Ivory-Billed Woodpecker, a rare bird whose existence is suspected but not unassailably proven.

Ionut Alex Chitu notes on the Google Operating System blog that the recent replacement of the "PDF" label in the Google Docs "items by type" menu with the "Files" label suggests that Google Docs will allow users to upload any kind of file. Such a move is consistent with the requirements of a generalized online storage service.

In and of itself, a minor change of this sort isn't enough to confirm the existence of GDrive. But at least one Google employee has already publicly stated that Google is developing a cloud-based storage service to compete with Amazon's S3.

At the Interop trade show in May, during the Interop Enterprise Cloud summit, Google product manager Mike Repass reportedly said, "We started out Google App Engine as an abstract virtualization service. Our static content solution is something we're shipping soon."

And in January, Brian E. Ussery, director of search engine optimization at Search Discovery, found a reference to GDrive in a JavaScript localization file associated with Google Pack, Google's free software bundle.

The file, which has since been altered to remove any reference to GDrive, described GDrive thus: "GDrive provides reliable storage for all of your files, including photos, music and documents. ... GDrive allows you to access your files from anywhere, anytime, and from any device -- be it from your desktop, Web browser, or cellular phone."

Sightings of GDrive go back at least to 2006, when blogger Corsin Camichel came across an early version of GDrive called "Platypus."

As to why GDrive's arrival is taking so long, there's not only the technical challenge of integrating GDrive with Google's ever expanding lists of services but there are also policy and pricing harmonization issues. If GDrive is to work across all services, Google needs to provide consistent pricing and storage limits.

Google's Gmail for example, currently provides users with almost 8 GB of free storage. Picasa Web Albums offer 1 GB of storage.

Google currently sells additional storage for these two services at the following prices: 10 GB ($20.00 per year); 40 GB ($75.00 per year); 150 GB ($250.00 per year); 400 GB ($500.00 per year).

Yet, YouTube accounts have no explicit storage limit. The service does limit file uploads to 2 GB for most users, however. Google Docs allows files to be up to 500 KB, plus up to 2 MB per embedded image, with a combined limit of 5000 documents and presentations, and 5000 images. Among other charges and quotas, Google App Engine provides 1 GB of free storage, with additional storage available for $0.15 per GB monthly.

Google didn't respond to requests to confirm the existence of GDrive.

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