Re: [greg] Is it possible to share data across two URLs
FWIW, it may also depend a bit on your server config. We have one site that has two projects hosted on the same account. The hosting firm calls this an add-on slot but in practice the second site is a another directory under the root. All the site layout files are in there, but the CMS folder remains in it's original (and single) location.
Apart from that, the process was seamless and easy. The client now manages both "sites" from within a single instance of CMSB.
And yes, I checked with the good people at Interactive Tools before I did this to make sure they didn't object. They didn't. They're cool. ;-)
J.