That would be nice, a review on desktop sharing tools.
In my company we use that so much, bc distances between workers. Also to show pre-releases to clients in other countries, or give a more detailed perspective on how the things are going.
But the problem of mostly of those services is the need of a standalone client, that mostly of them are only for specific platforms (specially Windows). There are some ones in java that can run from the browser too (like gatherplace.net, the one we're using now). This is ok, those works but so buggy.
We've researched about possibilities and just found that one as the best candidate for compatibility.
Ok, VNC is great. But we can't force our clients to install software in their fully-spyware computers, We need to give them extra support, and it becomes a headache.