Firewall+ Pro for Nokia N9 N950 can prevent unwanted call and SMS quietly, automatically and flexibly. Based on blacklist and whitelist, which support import from call log, SMS log and Contacts, flexible block rules can be applied as you want. With schedule mode, Time based rules are allowed, so set it up and forget! Also, rich blocked log informations and number matched count can be saved for checking.

http://store.ovi.com/content/260573

More screen caps: Here

This is an app fulfilled in my app request that could be able to block SPAM SMS in the N9/950

 

Source Maemo