in luke it does not say today, it say to day, 
lets translate chumkin style 
on this day you will be with me in paridise.  what day?
Hemera
of the last day of this present age, the day Christ will return from heaven, raise the dead, hold the final judgment, and perfect his kingdom 
i could be wrong, but  you know me  
  
 
but seeing this Jesus actully used the lest  amount of words he had to. he couldnt very well explain ressurection to the  guy.
he just got done teaching psalms 22, so he simply said" on hemera youll  be in  paridise.
I don't think I understand this interpretation, but that is nothing new. I get lost quite often.
In Luke, to day was translated from the Greek word semeron, which means "this very day". Not from the word hemera.
Ray's answer seemed much clearer to me. The comma was in the wrong place. Jesus told the thief today, that he would be in paradise with Him some time in the future.
Tim
tim,
 you are correct, but  when i study the word i go to the root and lok at all of it.
i could be wrong, but when looking into greek and how its been transliterated, i like to go deeper.
at crosswalk even the word hell  says its 
gevenna of Hebrew origin (01516) and (02011) 
Transliterated Word TDNT Entry 
Geenna 1:657,113 
Phonetic Spelling Parts of Speech 
gheh'-en-nah      Noun Feminine   
 Definition 
Hell is the place of the future punishment call "Gehenna" or "Gehenna of fire". This was originally the valley of Hinnom, south of Jerusalem, where the filth and dead animals of the city were cast out and burned; a fit symbol of the wicked and their future destruction.  
FROM:
Hinnom None 
Phonetic Spelling Parts of Speech 
hin-nome'      Proper Name Location   
 Definition 
Hinnom  http://= "lamentation" 
a valley (deep and narrow ravine) with steep, rocky sides located southwest of Jerusalem, separating Mount Zion to the north from the hill of evil counsel' and the sloping rocky plateau of the 'plain of Rephaim' to the south 
Jer 7:31
And they have built the high places of Tophet, which is in the valley of the son of 
Hinnomhttp://, to burn their sons and their daughters in the fire; which I commanded them not, neither came it into my heart
sorry for the confusion.