Sun's going to use Zuora's commerce-as-a-service billing engine for its cloud whenever the cloud finally gets here and provided, of course, that Oracle CEO Larry Ellison, soon to be Sun's new owner, countenances Sun's cloud adventure. Larry's not much of a cloud fancier, having previously dismissed it as a fad.

Zuora president and co-founder KV Rao, whose office lies within the shadow of the Oracle empire in Redwood City, believes that Sun will launch its cloud and that his deal with Sun will stay in place but he's just working on instinct leavened with hope.

Anyway, the way it stands Sun is supposed to integrate Zuora into its cloud computing products, which may reportedly see the light of day at JavaOne in early June.

Sun reportedly evaluated other prospects and lighted on Zuora for speed-to-market in introducing new cloud services, according to the CTO of its cloud enterprise Lew Tucker, which suggests that Sun has an aggressive launch schedule.

The Zuora widgetry will let Sun monetize its cloud with usage-based charges at consumption and since Sun is global it needs to collect sales tax.

Zuora's new Z-Billing 2.0, designed for subscription companies and more feature-rich than its predecessor, integrates a Taxation Module with three sales tax solutions; Sun will be using Sabrix.

Sun will also be integrating Zuora's cloud widgetry with Salesforce CRM to enable sales quotes.

Sun is Zuora's newest client. Since coming to market a year ago, the Marc Benioff-backed start-up has racked up 100 customers. Its Z-Payments solution accepts PayPal, credit cards and ACH electronic transfers. Z-Force is integrated with salesforce.com.