There are very few implications for accessibility and server-side scripting - the end product is what is required to be accessible, and is independent of the server-side technology that is available or used to generate the HTML.
There is one area where server side technology has an impact, and that is on code validation.
A problem that occurs repeatedly when developers are aiming for code validation lies in the use of ampersands (the "&" sign) in query strings that are present in links or form actions. While this may seem trivial, the requirement for ampersands to be encoded as "&" is important because server-side scripts rely on getting proper values in order to perform correctly. Browsers are written with the HTML standard in mind and communicate with the server with certain expectations - that of clean, valid code