What block numbers & hashes were discarded by the March 2013 blockchain fork? When exactly (GMT) were these blocks mined?
The following blocks were abandoned (along with a few more along that chain as the quickly dwindling set of 0.8.0 miners plugs along) when the 0.7 blockchain caught up with the 0.8.0 blockchain at 2013-03-12 06:19:32.  Thankfully, you can see that the 0.8.0 chain has slowed down to just one block in the two hours after 03:28:41 UTC.

Also note that, as I understand it, most transactions are showing up in both blockchains.

Source: https://blockchain.info/blocks/1363065244022  (where the ones to abandoned were labeled "Main Chain" until the current "Orphaned" chain caught up, at which point the labels swapped)

Update: I added 7 more blocks since the 0.8.0 chain was abandoned, up to 225461.  The rate of continued mining there is a bit less than one block per hour. 

Update 2: As of another day later, there haven't been any more blocks in the orphaned chain.  There is only one block at height 225462 (http://blockchain.info/block-height/225462) so the orphaned chain may end at a record 32 blocks.

Height  Time (UTC)             Hash

225461  2013-03-12 16:21:02  00000000000002d74c31d9c9f8e4768c0b51c3f145be07be7e77af0146144c30
225460  2013-03-12 15:05:56  00000000000002afb9088485b05a2b8a1dfa6b82e3e915fa0765879a05061461
225459  2013-03-12 14:36:39  000000000000036e459f26b1dc02683c9beeb061eedf18689995143354467245
225458  2013-03-12 12:18:23  00000000000000620d78c08bd345aa489b02a52c5f823f0324d3c42212577c24
225457  2013-03-12 09:48:00  0000000000000067fa40b890799ef9814e1e427abd5fc9f4751ffb3ef6512d14
225456  2013-03-12 07:59:29  000000000000031ce5f5c447dbe06ebd62f988c6718e1a17d14b9dcd8ff9605c
225455  2013-03-12 07:14:21  000000000000009d2dee89c7732b5bc912845d96a6bee38cab815949cfa60d23
225454  2013-03-12 05:17:11  00000000000000df96f272c3b1e9dd15272b55750966cbd239219b94756c73ec
225453  2013-03-12 03:28:41  000000000000031803e492a0103154d243c9945ef78dbdba42a1ecfdb5bc5dbb
225452  2013-03-12 03:05:29  0000000000000190f5944e56c52600e9d8d4d5416432e03b324bc85c51629bcd
225451  2013-03-12 02:06:07  00000000000003bdcc4424dea94de83e9f54ca158ae3eac59c2e97c2f90a32ad
225450  2013-03-12 02:01:28  000000000000026a105de544bfbe71bca0820ac3963ba132c75ec40411b5f162
225449  2013-03-12 01:50:05  00000000000001f15726ea57dc7702407a3ebc097ed801cb3d7b0e8a450807cb
225448  2013-03-12 01:38:10  00000000000001f9fd0b0cab82deca5f53030911b33ba7dd7ce3fd77ad2c5a55
225447  2013-03-12 01:34:55  00000000000000ec24f812807f81aadb7a665ef4ab8b8aa49df5ef789cdc13ff
225446  2013-03-12 01:30:40  00000000000000757de9173ee2f01c9f957c8aa3b4f71b901b0fa19683ab1fa1
225445  2013-03-12 01:14:54  00000000000000ec0df675972dddf0c2bdb1d436064672a6f0b79ce65ffcade6
225444  2013-03-12 01:07:00  00000000000003381ed79de2fa810c0e4f0e9c0cd5d307380b779e2b5ffa982e
225443  2013-03-12 01:05:42  0000000000000213874009d269b90be16ea5c1f6a83a79ae2be3813d8972a2a3
225442  2013-03-12 00:50:25  0000000000000229cd059490b7607ca4c191c52bb40405fa052c48d72bfda8b0
225441  2013-03-12 00:39:25  0000000000000372a4c37e27587255ca77a6377391c1974f13ea55ec1d3bc01b
225440  2013-03-12 00:20:11  00000000000003264ac7a6a74ca779997ee637b30f84debcb6ba6c26e2d09f4b
225439  2013-03-11 23:49:08  000000000000015aab28064a4c521d6a5325ff6e251e8ca2edfdfe6cb5bf832c
225438  2013-03-11 23:47:25  000000000000019881625f04eac2046512fa1e1bd7193f56f39595d802bbbd04
225437  2013-03-11 23:34:58  000000000000000016b3a292d63f9eea6b8177b8ba8dfd621d36fd828e5cb187
225436  2013-03-11 23:34:35  00000000000001a23b3f38106f210493795a1ef6b21dd559f87ada8dfc84181b
225435  2013-03-11 23:22:47  00000000000000947452b814ed008f750023e64c8fd03bb19b3865716eeb243d
225434  2013-03-11 23:08:53  00000000000002528688a366a9f42c07089268cd8a474961c49f787cb385807e
225433  2013-03-11 23:07:54  00000000000001b3c862fd66689712bc1cdd44fc004c008ada6c1b51367686f2
225432  2013-03-11 22:56:44  00000000000002c9e42c23f6eed2b9f9152a440610dcfaf992357c3cbff3689c
225431  2013-03-11 22:46:35  00000000000002d2012cc1b3fc0cceb8c156f0e698db40bf4413a210eca056c3
225430  2013-03-11 22:39:09  000000000000015c50b165fcdd33556f8b44800c5298943ac70b112df480c023