cut lines from log file and save it another file

Dears,
i want cut the lines from a log file. Example of the log file as follows..

May 27, 2011 5:54:51 PM com.huawei.ivas.utilities.sm.client.SMDeliverContrUtil isDeliverSM[Line:171]
FINE: [IP :10.50.14.23][ThreadID :smpp01:Receiver-17130][ThreadName :][Module:SMS.Util][Content:Whether to control SM deliver max number:fals
e]
May 27, 2011 5:54:51 PM com.huawei.ivas.utilities.sm.client.SMUtil addSysUpMsgLog[Line:531]
INFO: [IP :10.50.14.23][ThreadID :smpp01:Receiver-17130][ThreadName :][Module:SMS.Util][Keyword:97478360][Content:receive up message from [97
478360]. The message content is [C].]
May 27, 2011 5:54:51 PM com.huawei.ivas.system.SMResourceCache assembleSMContent[Line:328]
INFO: [IP :10.50.14.23][ThreadID :http-0.0.0.0-8080-Processor2][ThreadName :[97478360||20110527175451|1762]][Content:assemble sms parameter,
phonenumber:97478360, operator:4, label:sm_delete_accepted.]
May 27, 2011 5:54:51 PM com.huawei.ivas.system.SMResourceCache assembleSMContent[Line:397]
INFO: [IP :10.50.14.23][ThreadID :http-0.0.0.0-8080-Processor2][ThreadName :[97478360||20110527175451|1762]][Content:User's brandId is -1 who
's phoneNumber is 97478360]
May 27, 2011 5:54:51 PM com.huawei.ivas.utilities.sm.client.SMUtil sendInfoMsg[Line:233]
FINE: [IP :10.50.14.23][ThreadID :http-0.0.0.0-8080-Processor2][ThreadName :[97478360||20110527175451|1762]][Content:The short message of typ
e [109006] will be notified in real-time.]
May 27, 2011 5:54:51 PM com.huawei.ivas.utilities.sm.kernel.DeviceSelector getDeviceListFor[Line:476]

In that, i want to cut the lines based on timestamp and want to save the result into another file.This files is copied and overwriting from another machine every day and i want to get the only those line which is created since last change.
Please help.

Could you please explain "based on timestamp" , we really didn't get enough information to proceed. Make your requirement more clear and precise.