I had heared about this service before, but it seems they are really rolling it out this time:

https://www.google.com/hosted

It is basically gmail (2Gb webmail) but with your own domain name.

For fans of gmail this could be setup as your corporate webmail application. Safes a lot of headaches on the mail application server.

And with the labelling option I have found gmail to be at least as good as outlook for retrieval of data.

Will have to think about it for my next startup…