Here's another gaming to wortkstation comparison, it's for an old 8800 GTX but it still shows the performance dofferences like the V8800 comparison that was posted earlier.
http://www.techarp.com/showarticle.aspx?artno=539&pgno=9
The Quadro FX 4600 and GeForce 8800 GTX both use the same G80 GPU.
You can clearly see in the Specviewperf comparison in the middle of that link that teh FX 4600 which even has its GPU and RAM running about 15% slower then the 8800 GTX ( workstation cards unclock the ram and gpu compared to their gaming counterparts to help with their reliabilty and stability)completely wipes the floor over the 8800 GTX even after the 8800 GTX.
It also shows that while you can softmod (older cards atleast can't find any info on softmodding the newer nvidia cards) a gaming card to the workstation equivilent it may improve performance in some applications such as 3DS, Caita, Solidworks but may have hardly any effect in others such as Maya or USG NX.
This is more so because Maya and USG favour ATI hardware while 3DS favours Nvidia (I softmodded an HD2600XT a while back and Maya performance increase 360%) but you can also see the applications performance did go up in still doesn't approach anywhere near the performance that the actual workstation card gets in the same application and if you read the whole article there are still some features that either don't work or don't work properly after softmodding a card to the workstation equivilent and you also risk the softmod not working or even the card just not working seeing you have to mess with the BIOS.
I don't like that the workstation cards cost so much more but can't deny the performance difference and the soft modding shows that its not a simply matter of them making the card use a different driver and boom performance explosions so increase the cost.
Like has been said reliabilty/stability is a key factor in workstation cards so just think how much a gaming card would cost if they tested it and the driver with say 3DS Max to see it was working proerply then tested it on every version of Windows as well as Mac and Linux and deal with everyone that makes the software so that it gets certified to work with it. Then tested it with every single other producitivty 3D application then when all done moved onto the next gamging card and did the same thing. They find out that this next card has a problem with something in say Maya (might be minor or major) so they address it in the driver and finish testing. Well now they have to go back and test that other card with everything again to make sure the change they made didn't stuff something up for that.
Gaming cards wouldn't be so cheap would they and this is what they do with the workstation cards. Obivously sometimes there are some things they can't change without effecting something else and end up not being able to guarnatee that every card in the series will work with every application (which you can see looking at certification lists for the softwares where not all the workstation cards even from the same series are listed).
It sux the cards cost so much more then gaming but there are reasons for it. There is definately justification for them costing quite a bit more then gamging cards though I still think they should be a little cheaper then they are.