Slicing a psd is a web designer's work or a web developer's? Please discuss.

It should be the job of a front-end developer and not the designer nor the back-end developer

Actually it is the designer's job, but a developer should have no problem with that even if it is not sliced.
The developer compliments the designers and sometimes he is obliged to do some more work instead of wasting time and requesting a sliced version.

I think designers are specialized in designing.
That is their niche skill.
Web developers are meant to develope the layouts designed by the designers.
That's developers' niche skills.
However, nowadays, companies are trying get two different skillsets from one single resource to save money.
Hence, designers are asked to develop the designs and developers are asked to design layouts.

slicing a psd is a web designer's work not aweb developer's as i see

It is part of Frontend developer's work. But I believe a backend developer and graphic designer should have abilities to slice a PSD as an additional skill.

Web designer for sure, one should be a jack of all a$$ :)

I believe it's the job of web designer, but most web designers deligate this task to web developers.