is there any MumSMS for P1i? it's a great application which I am using in N70.. I wonder if it also exist for UIQ3?

Yes Bro,that's a wonderful application for UIQ 2,...
For UIQ 3 now we have Magic Message Manager,I have found it in our forum here.
The functions similar to MumSms,but different in interfaces and setting.
Just find and try it Bro.