You don't include an example, but if you don't have a Z-offset or timezone, and assuming you don't want durations but just the basic time, then maybe this will suit you:
import datetime as dt
>>> dt.datetime.strptime('1985-04-12T23:20:50.52', '%Y-%m-%dT%H:%M:%S.%f')
datetime.datetime(1985, 4, 12, 23, 20, 50, 520000)
The strptime() function was added to the datetime module in Python 2.5 so some people don't yet know it's there.
Edit: The time.strptime() function has existed for a while though, and works about the same to give you a struct_time value:
>>> ts = time.strptime('1985-04-12T23:20:50.52', '%Y-%m-%dT%H:%M:%S.%f')
>>> ts
time.struct_time(tm_year=1985, tm_mon=4, tm_mday=12, tm_hour=23, tm_min=20, tm_sec=50, tm_wday=4, tm_yday=102, tm_isdst=-1)
>>> time.mktime(ts)
482210450.0
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