To follow up on this, I believe you would receive bonus power points for each class equal to half your key ability modifier times the number of levels in the class. Thusly, a level 4 psion and level 1 psychic warrior, with 18 INT (+4 INTMOD) and 14 WIS (+2 WISMOD), gets +8 pp for his Psion levels and +1 for his Psywar level. I can see how one might read that he instead gets +10 pp from his INT and +5pp from his WIS for being character level 5, but I'm fairly certain this is incorrect; even though the "bonus PP by character level" table is outside of the classes sections, I don't think you're meant to be able to count all your multiclass levels multiple times (potentially as many as three, since there are that many key modifiers that a sufficiently multiclass character could have; a Venerable character might have 21s in all three abilities, which would add up to a heck of a lot of PP). Please let me know if I'm figuring this right.