That review actually shows that the FireGL is competant at gaming, with it performing well against the GTS, in fact it was so interesting that it did so well that it was worthy of passing along to other people in PMs when it first launched. Their test (be it a small one) shows that the FireGL (HD2900Pro based) does remaing competative with it's Geforce Gaiming rival the GTS-320, performing basically the same as the HD2900Pro does;
That being said, the main thing to remember is that the heavy lifting is still mainly done by CPU/Memory/HDD, and if you look at the results of the first workstation test (which is a work-unit/time test, not fps), it shows that the actual output performance is very much unaffected by the graphics card where the GTS outperforms the Quadro, the main thing that the workstation cards help with is the viewport acceleration for previews etc, and they add a few tweak features in the drivers including support for higher levels of AA. This will not affect final output quality or speed.
The 8800 GTS would be better for high rez gaming (ie. 1900x1200), and when you AA for increased visual gaming quality, but I think I read somewhere that the Ati architcture works better for workstation apps (not 100% sure though).
I wouldn't put the GTS-320 in there for high res gaming, maybe the GF8800GT/GTS-512 and HD3870, but not the GF880GTS-320 which just dies as if jumping off a cliff once you kick in the AA/Res, which is the same that the HD2900Pro-256/V7600 would experience though, so it's not like either are really suited for high end gaming.
As for the last comment, that does seem to be the case for pretty much the first time in a long time (long have the Quadros reigned unchallenged), however it's still a here/there kinda of things with both doing things a little better than the other. The main thing is performance/value is hugely in the new HD series of FireGL's favour, but there are still alot of reasons to buy a Quadro, especially for certain apps that play favourites, and also for some driver tweaks that favour one or the other in some apps.
At some time you have to decide what you need, and IMO unless you absolutely need a workstation card, then getting a solid gaming card saves you money and usually gives you more stable gaming performance (if you thought driver support / bug fixes for gaming cards was slow, just wait for it to come to official workstation drivers).