You can get the new YouTube client by going to m.google.com in Web and tapping on 'YouTube' (of course). It's a 2.5MB download and installs on top of any previous version. It's shown as available for all Symbian handsets, including S60 3rd Edition and S60 5th Edition devices, so go download now, especially if you have a higher resolution touchscreen phone.
This has been a bit of a hole in the 2010 Internet pretensions of the Nokia N8 and C7, so it's great to see it finally plugged, and in style. The video stream is definitely higher quality than the old up-sampled QVGA, introduced when the client first appeared back in 2007, but it doesn't seem to be as crisp and smooth as that on the higher resolution Android phones - if you've got the tech details on this, please chip in. Thanks.
Steve Litchfield, AAS, 8 Dec 2010
PS. Hat tip to Jay for the heads-up