I have recently moved house, and phoned up BT yesterday to install a new line.
They quoted me 124.99 for a new line install.
I mentioned the fact that they were offering install for £29.99 last month, and asked whether they could still do it.
She went away to speak to a manager, and came back with a yes, with a bit extra off with the VAT changes!
You may be aware that BT were offering cheaper line install last month, but there is currently no advertised promotion in place, as that offer ended on the 31st of December 2008.
Useful if you don't want/can't get Sky to rebate the line install charge.