They can also research them, using no feats, but at an EXP cost:
Although it's not spelled out that independant research skips the powers known cap, there isn't really anything that says a Psion can't know more powers than is listed.
Also, note that the Psicraft check is kinda pointless - at first level, a psion will (usually) have 4 ranks in psicraft, and 3 or 4 points of intelligence bonus, and can thus take 10 for 17 or 18 (1st level powers have DC 11). At 3rd, that's 6 ranks, probably the same INT bonus; can take 10 for 19 or 20 (2nd level powers have DC 12). After about level 6, a Psion taking max ranks in Psicraft with an Int mod of 4 will be able to research, with no random chance of failure, any power on the list that the psion would be able to manifest (9 (ranks) + 4 (int) +1 (minimum roll) = 14; a level 4 power has DC 14). With Skill Focus(Psicraft), that drops all the way down to level 1: 4 (ranks) + 3 (Skill Focus) + 3 (Int Bonus) + 1 (minimum roll on d20) = 11; DC for level-1 power is 11.