What is special about this particular release?
A small item in the Changelog talking about a newships feature. In detail this means some extended processing of the file "ttdpatch.grf". After the first 48 sprites (presignals) it allowed putting a new type of sprite, called "pseudosprite" into the file. These pseudosprites could further be distinguished into something called "Action 0" to "Action 3" - the foundation of NewGRFs!
While 1.8.2 alpha 4 allowed only a single NewGRF file, which also contained other stuff in front, the basic layout of Action 1-2-3
chains was settled. (Though "chain" might be an exaggeration since there were no variational or random actions, so you could not chain them.)
This first format experienced some syntactical changes throughout the process, so the original format and also the format used by TTDPatch 1.9 (2002-10-29) is not supported (anymore) by todays TTDPatch and OpenTTD. It took till TTDPatch 2.0 (2003-09-26) to settle for something called GRF version 2.
Independent of these releases, today seems to be most appropiate to party the 10th anniversary of NewGRFs!
So far, for the general announcement. Do you want to know more? Do you want to know how the first version of NewGRF specs for TTDPatch 1.8.2 alpha 4 looked like?
Take a look at the following links and summarized history of 10 years of NewGRF spec evolution. (There are some more details in the beginning, since the announcements were kind of bigger and the changes were faster; later on bigger stuff was done, which took months, so you cannot give a meaningful date.)
Also, feel free to share your NewGRF-related stories and memories

2002-08-11 1.8.2 alpha 4
[list]
[*] Only single grf file (ttdpatch.grf), first 48 sprites were presignals, then real NewGRF stuff starts.
[*] Supporting action 0, 1, 2 and 3 for ships.
[*] Though some changes in the format were made up to 2.0, the basic Action 1-2-3 method is settled.[/list]
[list]
[*] Mailing list: http://lists.ttdpatch.net/ttdpatch/200208/msg00032.html
[*] Forum: http://www.tt-forums.net/viewtopic.php?p=1677#p1677
[*] Specs: http://hg.openttd.org/developers/frosch ... newgrf.txt[/list]
2002-10-29 1.9
[list]
[*] First stable release with support for NewShips.
[*] Compared to 1.8.2 alpha 4, Action 4 is new and there are some other marginal changes.[/list]
[list]
[*] Mailing list: http://lists.ttdpatch.net/ttdpatch-anno ... 00002.html
[*] Specs: http://hg.openttd.org/developers/frosch ... newgrf.txt[/list]
2003-12-10 1.9.1 alpha 5
[list]
[*] Configuration of grf files via newgrf.txt (no longer everything in ttdpatch.grf)
[*] Action 5
[*] Grf parameters, Action 6 and 7[/list]
2003-01-13 1.9.1 alpha 13
[list]
[*] Random and variational action 2 (types 80 and 81)[/list]
[list]
[*] Mailing list: http://lists.ttdpatch.net/ttdpatch/200301/msg00049.html
[*] Forum: http://www.tt-forums.net/viewtopic.php?t=1991
[*] Specs: http://hg.openttd.org/developers/frosch ... newgrf.txt[/list]
2003-09-26 2.0
[list]
[*] GRF version bump to 2 (all previous files are considered incompatible)
[*] All 4 vehicle types, Action 0 to A as we know them today basically (well, lots of additions in the details)[/list]
[list]
[*] Mailing list: http://lists.ttdpatch.net/ttdpatch-anno ... 00002.html
[*] Specs: http://hg.openttd.org/developers/frosch ... newgrf.txt[/list]
2003-10-12 2.0.1 alpha 3
[list]
[*] 40+x variables[/list]
2004
[list]
[*] callbacks (2004-01-25 2.0.1 alpha 11)
[*] 15bit callback results (2004-11-22 2.0.1 alpha 40)
[*] new stations
[*] canals
[*] bridges
[*] houses
[*] nforenum
[*] grfmaker[/list]
2005
[list]
[*] advanced varaction2 (2005-07-09 2.0.1 alpha 54)
[*] 60+x variables (2005-08-07 2.0.1 alpha 56)
[*] sound support (2005-08-21 2.0.1 alpha 57)
[*] cargo translation table (2005-10-21 2.0.1 alpha 66)
[*] industries
[*] cargos
[*] townnames[/list]
2006
[list]
[*] start of grf version 7 (2006-01-22 2.0.1 alpha 70)
[*] UTF-8 support (2006-02-13 2.0.1 alpha 73)[/list]
2007-2008
[list]
[*] Dark age of NewGRFs
[*] There is nothing really new in these years. Previous developers left the projects; new ones had not yet caught up with NewGRF stuff.
[*] In retrospect there seem to be quite some additions which were unnecessary/wrong due to general unknownness under the remaining/new developers.
[*] OpenTTD 0.6.0 (2008-04-01): Approximately GRF feature parity between TTDPatch and OpenTTD. (the missing bits were basically unused)[/list]
2009
[list]
[*] begin of NewGRF spec consolidation (reviewing of existing specs, discovering inconsistencies between Specs, TTDPatch and OpenTTD)
[*] engine pool (up to 64k vehicles)[/list]
2010
[list]
[*] airport tiles
[*] railtypes
[*] objects
[*] Action 14 (parameter GUI)
[*] NML[/list]
2011
[list]
[*] GRF version 8[/list]
2012
[list]
[*] nfo32 and GRF container 2[/list]