Question: I am curious to know why should a Database person learn LINQ. How can it be useful.

Answer: 
"Know your enemy" ?

OTOH, out of interest. I'm learning more about XMl, XSLT, XSDs etc because I can see a use for them as a database developer.
This question also prompts me to ask, if LINQ becomes immensely popular, will server side developers know SQL as well as their predecessors did?