My take on this is Edge Rails is not what *I* use for development, but what is currently being developed by the core team. Kind of like getting latest from the code repository. You might also call it a development build. Probably loosely analogous to Debian Unstable.
Peace, Phillip
As far as having all the goodies in 2.0, if yr on Edge Rails... you
have them. 
Hope that answer helps.
RSL
"Edge" comes from "bleeding edge," meaning you have the very latest version of Rails. To say "version," though, is a bit of a misnomer, as edge never corresponds to any specific version. As Russell mentioned, if you have edge, you will always have the features of the latest proper version, but the crucial difference is that you will usually also have *more* features with edge. This is because the edge is the main development trunk, meaning the place where all the work on Rails is actually occurring. Every so often, the core team will go through the latest changes on the trunk (edge) and select a number of them to be included in an official release, which, as Ryan mentioned, then gets created as a branch of the trunk (snapshot) such as 2.0.
In short, official versions of Rails are released as gems. To use edge, you would need to explicitly export the Rails trunk from the official code repository. Since this only happens if you intentionally do it, and since you probably followed some instructions that had you install the Rails gem, you're most likely not using edge. More specifically, if all you did was install the Rails 2.0 gem, then you are decidedly not using edge.
Ian
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