Proxy certificate revocation.
Despite its convenience for the computational Grid, Proxy Certificate revocation process involves a series of issues which must be known by potential users before its adoption in a production environment. Recommendations about such issues will be explained next.
First of all, Proxy Revocation must be understood as a process related with Authentication mechanisms and even though it could be useful for implementing blacklist-like solutions they can not replace Authorization mechanisms. In fact, Grid OCSP in general and Proxy Revocation in particular are the building blocks for the so-called validation function of the authentication process, which complements the authorization process. Notice the one-way relationship between both processes: if a Proxy Certificate is found as revoked by a validation function, then the authorization process will never take place; on the other hand a valid Proxy Certificate may be unauthorized to access a certain Grid resource.
Should a Proxy Certificate be revoked, then its issuer takes the role and responsibility of a CA. However, due to the security implications and the complexity for implementing and automatically managing such mechanisms, it is highly recommended that only End Entities revoke their own Proxy Certificates.
If a third party is required to perform this process (i.e. resource owners and local security administrators), it is recommended to notify of such revocation the corresponding End Entity from the Proxy Validation Path so appropriate counteractive actions can take place. However, as mentioned previously, third party revocation is not a recommended practice from a security point of view.
Future development of a comprehensive Grid Credential Validation System allowing for the provision of complete certificate trust decisions is very likely to take place in the short term; however, as a first step, CAs and OCSP Responders should be enabled to manage and provide respectively Proxy Certificate revocation information, which will play an important role in such systems. 
The better balance between security and usability in such mechanisms, the most useful they will be for potential Grid users.