Many people are running Tor relays on virtual servers "in the cloud", using VPS providers like Amazon EC2, Rackspace, Linode, etc. Most major VPS providers offer virtual servers in multiple geographical locations, but they are still controlled by one entity, which of course ultimately have total access to any storage (RAM and disk) of any customer VPS, easily compromising any crypto key material.
I don't think it is necessarily that bad to trust VPS providers (and they often are a great way to get excellent bandwidth cheaply), but I feel it would be important to somehow make sure Tor users don't end up having circuits that all go through relays running on e.g. EC2. Same way you're supposed to group your own relays with MyFamily.
Is there any way currently to do this, or are there already some safeguards in place?