For anyone stuck to very old Intel 830GM or 845G chipsets, the xf86-video-intel 2.20.3 driver release now restores acceleration support by default for the vintage hardware. "Enable acceleration by default on 830gm/845g. The GMCH on this pair of chipsets is notoriously incoherent, so the GPU is almost certainly going to hang at some point, though unlikely to hang the system and should automatically disable acceleration (and thence behave identically as if the acceleration was disabled from the start). Option "NoAccel" can be used to disable all 2D acceleration and Option "DRI" can be used to disable all 3D acceleration."
In addition, the xf86-video-intel 2.20.3 point release updates DPMS book-keeping after mode-setting, avoids overlapping GPU/CPU damage after ignoring CPU damage in considering the placement of the operation, and a fix for vertex book-keeping on Intel "Gen4" hardware that was leading to corruption in the command stream.
There's also more SNA acceleration architecture fixes with Chris Wilson committing 41 changes to this point release update. This release also has the early Intel Haswell code.
Find more details on the xf86-video-intel 2.20.3 update in this mailing list announcement.