This tag merge will affect a lot of questions, so I think we should discuss it here before doing it.
To be clear:
Should we do it?
The companies may have recently merged (or changed names - I don't know offhand), but my ATI Radeon graphics card was made by ATI, not AMD. Have the drivers merged as well?
Certainly the lspci still reports:
01:00.0 VGA compatible controller: ATI Technologies Inc Radeon RV250 If [Radeon 9000] (rev 01)
If I'm asking for help about this, I'm not going to know to use a tag referring to a new company name that my driver (or card) isn't reporting. I'd vote to leave the tag as it is and let the amd-graphics tag refer to the new stuff that actually comes from amd (or reports so). Can new marketing catch up with old hardware? I doubt it is motivated to do so, yet old hardware doesn't change.
Since all the recent AMD distributed graphic cards are in fact labeled as AMD Radeon for example, I'd say we should go for it.
Googling for ATI results in the first four entries to be linked to http://amd.com and have a lot of AMD references in them. It think it is time to merge the tags as proposed if it happened already.