My bad, I was wrong. According to the "help" part of the app, iPlayer only supports Vodafone and 3 but it can work on T-mobile and O2.
No worries.
I'm using iPlayer well on my N97 / O2 (don't laugh) which, apart from the laggy GPS, now works really well.
However, this an Android forum, so enough about Noka already.
The reason I'm on this forum is because I just took delivery of my new Archos 5 Internet Tablet, running Android. After all the messing around with the N97, the Archos is delicious. I bought it from QVC, during the presentation on Saturday, delivered Tuesday - wonderful.
I mention the presentation because the MD of Archos said (kind of sheepishly), in response to a question asking if iPlayer was included, "No. But it will play downloaded files transferred from your PC".
Beebplayer works quite nicely on the Archos. There are some improvements which can be made, but it does work, so full marks to Dave Johnstone.
One bonus thing - the implementation of iPlayer on my Nokia only allows streaming using Wlan, not HSDPA. Beebplayer works on HSDPA. When I say "works", remember the Archos is not a phone. So you have to "tether" the Archos to the phone first. Then the Archos is using the N97's HSDPA connection.
Very liberating.