Hosted Kolab?

[Alex]

I'm looking at ways of outsourcing some of my companies various hosting 
tasks we would normally fire up a xen virtual server for, and was 
wondering if anyone offers kolab hosting?

For example, I'm looking at "openx hosted" to serve our advertisements 
and "gradwell" in the UK to host our VOIP PBX.

The advantages to me would be:

+ Software upgrades, including security upgrades
+ Managed backups
+ Don't have to worry about hardware faults

Does anyone know if a solution exists, or if it doesn't exist for a reason?

Thanks,

Alex