#!/usr/bin/env python
fh=open("file")
s=""
f=0
for items in fh:
    items=items.strip()
    if f and  items.startswith("2009"):
        if ";" in s:
            ind=s.index(";")
            print s[:ind] #print from start till where ; is
        else:
            print s 
        s=""  
        f=0        
    if items.startswith("2009"): 
        f=1 #set flag        
        print items,
        continue
    if f and not items.startswith("2009"):
        # join up those lines that doesn't start with 2009
        s=s+items
fh.close() #close the file

# more file
2009-05-27 02:37:27.283 The quick
brown fox;
The quick
brown fox
2009-05-28 10:10:28.000 Mary
had a
little lamb.
2009-06-01 19:37:29.000 Jack and Jill ran up the hill;
adsf
sldkfdf
2009-05-28 10:10:28.000 Mary test
tester fmsd
2009-05-28 10:10:28.000

# ./test.py
2009-05-27 02:37:27.283 The quick brown fox
2009-05-28 10:10:28.000 Mary had alittle lamb.
2009-06-01 19:37:29.000 Jack and Jill ran up the hill; adsfsldkfdf
2009-05-28 10:10:28.000 Mary test tester fmsd
2009-05-28 10:10:28.000