ha! Waiting for 2...e6 before playing 3.g3 is a little trick of Closed Sicilian players, when they suspect Black won't play straighforward ...d5 (in another thread I argued that playing immediate e6/d5 gave Black too much equality, meaning that winning can be difficult even when he's much stronger). With ...e6 first instead of ...d6, the point for White in the Bg7 lines is that Be3 will come with tempo as c5 is not protected. One standard recipe for Black is to play a Kan setup with a6/Qc7 (avoiding the tricky g3 taimanov) and then playing with ...d6/Nf6/Be7, leading to complex and unclear position. Of course, after 1.e4 c5 2.Nc3 Black is tied by his main answer to the Open Sicilian, so there is no "best" setup yet. 

Edit : Mr. Palliser is in da house, hopefully he may comment on the soundness of ...e6/d5 vs closed siclian?

Quote:

No misunderstandings  - 2...a6 is "Simply a strong move!" - at least according to Endre Vegh in NIC Yearbook 96

Of course there are interesting games and analysis in the "Anti-Sicilian-Section" of Chesspublishing for subscribers - e.g. the following explanation to 2...a6:

"It is generally played by Najdorf players, who do not want to be tricked into another Sicilian with White following up on 2 Nc3 with 3.Nf3 and 4.d4. ... What can I say? 2...a6 is absolutely fine, but far from necessary, even if you want to play the Najdorf. If I was sure my opponents would all meet 2.Nc3 with 2...a6 I would consider playing 1.e4 again because I like the fact that White tends to get quite a big lead in development, and has several options pure Closed Sicilian with g3, Bg2, d3 various lines with an early d4 and Grand Prix Attack lines with f4, some of which are even quite exotic-with an early g4."

Exactly. In many sicilians Black catches up "later" with development, and sometimes he can be happy with an a6-b5-Bb7-e6-Nf6 setup, while preventing the 1.e4 c5 2.Nc3 Nc6 3.Bb5 Nd4 4.Bc4 Grand Prix. But this is another opera ; with respect to the Original Post it was meant to say that Black had another possibility if he was unsure of Nge7 vs Nf6.

Two remarks, rather basic but perhaps useful, regarding the closed sicilian 1.e4 c5 2.Nc3 Nc6 [2...a6] 3.g3 : 

1. Black can always play in classical fashion with ...e6, Nf6,Be7 and d5. It was considered suboptimal in the 70s, as people preferred the g6-Nge7 setup to delay the effects of White's kingside pawn roll, but I can't see anything wrong with this setup. Moreover, it's a good way to play a fresh game, since White is more than used to the g6-Nge7 setup.

2. if Black plays with g6-Bg7 against the Closed, he may then chose to put his Knight on e7 or f6. The setup with c5-Nc6-d6-e6-g6-Bg7-Nge7 is (in my view) always reliable, but sometimes Black can improve by playing Nf6, especially when White plays Be3 while Black's knight is still at g8. For instance :

1.e4 c5 2.Nc3 Nc6 3.g3 g6 4.Bg2 Bg7 5.d3 d6 [5...e6 limits Black's play after 6.Be3 attacking c5] and now :

a) if White plays in classical fashion by 6.f4, Black's 6...Nge7 is appropriate since d4 is controlled (e.g by ...Nd4 possibly followed by ...Nec6 when White threatens to push d4). Black keeps the option of playing ...f7-f5 after h6/Be6/Kh7, and the Knight also jumps to f5 with good effect after White's e4-e5. There are a couples of lines to know, but this setup with ...Nge7 is a good deterrent to White's 6.f4

b) of late, White rather plays 6.Be3. if 6...Nge7 she can play 7.Qd2 and cause some minor trouble on h6 : Black has to wait for f4 before castling, but it's still playable. On the other hand, 6...Nf6 prevents 7.Qd2 because of 7...Ng4, so Black has to play something like 7.h3. White may pretend to have lured Black into ...Nf6 after 7...0-0 8.f4, but in fact Black has the initiative after e.g. 8...Rb8 9.Nf3 b5 10.0-0 b4 11.Ne2 Nd7. If White tries 8.Qd2 instead, Black can either play the fine 8...Rb8 followed by b5-b4 (Blacks queenside initiative and White's h2-h3 makes a full-blown attack with Bh6 and h4 irrealist), or he can also control the centre with e.g. 8...Nd4 9. Nd1 9...e5 10.c3 Ne6.

I don't know for the Grand Prix Attack, but in the Closed Sicilian Black can have a good game without resorting to subtleties, just playing by principles (agreed, subtleties come later in the 6.f4 Nge7 lines, surely good people can further explain). Also 1.e4 c5 2.Nc3 a6 is a good option if it fits your main answer to the Open sicilian after 3.Nf3.