Writing a utility class for converting between datetime and timestamp
Let's examine the code:

#!usr/bin/python


you don't need to execute the code directly, so why this line?

class datetimeutil:
    @staticmethod


why a class with static methods? Keep it simple, write global functions. You already have the module which encapsulates the functions.

    def strtodt(text):


I don't like too much the names of these functions. I know that also python uses ugly names (words without any separator) but I think you could improve this... for example: str_to_dt or str2dt seem better to me.

About the functionality. Managing dates is a quite difficult task. The python library in my opinion makes a great job in distinguishing naive and aware datetimes. Your wrapper module simplifies this by considering each naive datetime as a localtime (if I understand it correctly). I think it is not good to hide this decision in your code. Explicit is better, even if it could me more verbose.

Also I think you missed the timedelta.total_seconds function, which could be used in your code.