Steve, It appears to be, we were actually playing around trying to get my E71 (&N82) working with the iPlayer 1.5 version.
What we discovered is that not only is iPlayer device dependent, ie N96, but also appears to be somewhat dependent on your phone network too.
For example:
iPlayer 1.5, Nokia N96, Orange Sim, Realplayer default set to 3G
Streaming WiFi: Yes
Streaming 3G: Yes
Downloads WiFi: Yes
Downloads 3G: Yes
iPlayer 1.5, Nokia N96, Vodafone Sim, Realplayer default set to 3G
Streaming WiFi: Yes
Streaming 3G: No
Downloads WiFi: Yes
Downloads 3G: No
iPlayer 1.5, Nokia N95 and N82, Orange Sim, Realplayer default set to 3G
Streaming WiFi: Yes (but Realplayer needs to be set to Wifi manually)
Streaming 3G: Yes
Downloads WiFi: No
Downloads 3G: No
iPlayer 1.5, Nokia N95 and N82, Vodafone Sim, Realplayer default set to WiFi
Streaming WiFi: No (Switch to WiFi message displayed, even though RP default set to Wifi)
Streaming 3G: No
Downloads WiFi: No
Downloads 3G: No
Results for my E71 on Vodafone (with javascript modded iPlayer) were the same as the N95, didn't try with Orange as I was refused to let my brother stick his Orange sim card in after it screwed up all the settings on my N82.
So
1: The N96, regardless of the access point selected in realplayer streaming settings, the browser will carry through wifi connection to realplayer
2: Orange allow you to stream over 3G, but with there dataplan costing �8 per month for 30mb (or one episode of Eastenders) it will be a rich man that uses it.
3: On the N95, the javascript used to block 3G from unsupported networks basically blocks WiFi too, as unlike the N96 the browser doesn't allow the WiFi to pass through to Realplayer.
4: We could only get downloads to work on the N96, on the N95 (orange sim) they would download, but not play (due to DRM?)
So for now on my E71 I will continue to use my modded version of iPlayer 1.0, now further changed to remove the annoying 'Update' latest version message. (simply open widget.html in a text editor and remove the following code)
<div id="update-available">
<h3>Update Available</h3>
<p><a id="update-link" href="#">Click here to download</a></p>
</div>