With our site redesign to go along with ProofBuddy 2.1, we also added a new link that will always download whatever the latest version of ProofBuddy.
www.proofbuddy.com/latest.zip will always be the latest stable version of ProofBuddy. As of this post it's 2.0.4.
www.proofbuddy.com/latest.zip?beta will always link to the latest version, including pre-release versions. When there's a pre-release version like there is now with version 2.1.beta it will download that file. When there isn't an active pre-release version it will download the most recent stable version.
The reason we did this, aside from making it easier to keep the downloads page updated, is that it is planned for a future version of ProofBuddy to be able to automatically update itself.