Skill Focus and other Skill Feat Bonus stacking?

[Tharen the Damned]

Ok, I have never though about stacking the Bonus from Skill Focus (say for Spellcraft) and from the Feat Magical Aptitude.
Do they stack (and give a handy +5 to Spellcraft), as they seem to be unamend bonuses?

 

[James McMurray]

Yes, as unnamed bonuses from different sources they stack.