[R] reshape with two time variables

[Neil Stewart]

I have a data frame in wide format that I'd like to convert to long format.
For example, in wide format I have:

	id	A1B1	A1B2	A2B1	A2B2
1	1	400	475	420	510
2	2	390	500	470	472
3	3	428	512	555	610
4	4	703	787	801	822
5	5	611	634	721	705
6	6	543	522	612	788
7	7	411	488	506	623
8	8	654	644	711	795

A is one repeated-measures variable with levels 1 and 2. B is a second
repeated-measures variable also with levels 1 and 2. I'd like to end up
with:

	id	A	B	value
1	1	1	1	400
2	2	1	1	390
3	3	1	1	428
4	4	1	1	703
5	5	1	1	611
6	6	1	1	543
7	7	1	1	411
8	8	1	1	654
9	1	1	2	475
10	2	1	2	500
11	3	1	2	512
12	4	1	2	787
13	5	1	2	634
14	6	1	2	522
15	7	1	2	488
16	8	1	2	644
17	1	2	1	420
18	2	2	1	470
19	3	2	1	555
20	4	2	1	801
21	5	2	1	721
22	6	2	1	612
23	7	2	1	506
24	8	2	1	711
25	1	2	2	510
26	2	2	2	472
27	3	2	2	610
28	4	2	2	822
29	5	2	2	705
30	6	2	2	788
31	7	2	2	623
32	8	2	2	795

I've been working with reshape and with the reshape package, but with no
success for the two-time-variable case. Can anyone help please?