I have reading about variety of frameworks for web applications like OpenRasta, Django, CodeIgniter etc. It is a passion of developers to dip their hands on any new technology, but from the job-seeker's point of view, what is the significance of these new buzzes. Is it better for a job-seeker to stick with the standard frameworks like ASP.NET, Rails etc., or devote time on other open-source frameworks as well?
If you are looking to do freelance web development it can be worth putting time into becoming intimately skilled with certain frameworks. Being able to advertise yourself as a knowledge expert can be good for getting the jobs where companies are looking for work on those specific frameworks.
However, if you are just looking for a full time job someplace, you really need to be focused on becoming a well rounded developer with general developer skills & fundamentals; algorithms, data structures, database design, software patterns (MVC, MVP, MVVM), development life-cycle, etc, etc.
I think it's best to have a solid foundation in software development first, then your preferred languages. If you understand software design and are a strong analytical thinker, you can pick up languages as you need them for a task.
Once you become solid in your chosen languages, frameworks fall in place when you need them for a job. It helps to have an idea of the methodologies behind the frameworks and an understanding of how they fit into good software design. If you know a job requires the use of certain frameworks, brush up on them. If you have the necessary background, it won't be difficult to demonstrate that you can come up to speed rather quickly on any framework a job requires.