Sun is now offering a new virtualization service that will let ISVs run their Solaris apps in a multi-tenant on-demand environment without having to rewrite any code.

The trick is in Solaris’ Containers virtualization and its xVM widgetry.

The new Solaris On Demand program will provide third-party hosting complements of NaviSite, AT&T USi Communications and NTT Europe Online.

There’s a free 90-day proof-of-concept environment promising 99.5% guaranteed uptime available to try out.

Either Sun or one of the hosters will manage the applications and Sun is promising to help with the transition.

Cost will ultimately depend on the resources needed.

There are something like 6,500 commercial Solaris ISVs.