Such a move would clearly be popular among shareholders – Salesforce.com’s share price jumped 5% in pre-market trading on Monday, when the rumor surfaced, although Google’s remained flat.

According to reports the alliance could take the form of an on-demand service that integrates Google’s online services such as email and instant messaging with that of Salesforce.com.

Salesforce.com has always used a combination of its CRM services and Google applications such as Google Maps to demonstrate the power of application mash-ups and the two already promote the other’s services following the the launch of a Salesforce.com facilities to take advantage of Google’s AdWords platform.

Salesforce.com would have the most to gain from any partnership given its relative size, a belief that appears to be reflected in the static share price following the news, especially as Salesforce.com’s latest financial results indicate that growth is becoming more expensive.

For Google a partnership could be part of a long range plan to counter Microsoft’s emerging SaaS plans because although the Microsoft Live services are insubstantial at the moment Microsoft is throwing the weight of the company behind the concept of software and services and SaaS has finally become an important strategic development.

By working together Google and Salesforce.com could offer a package of Google productivity and Salesforce.com business applications that could present an alternative to the Microsoft Office and business applications combo.