I don't know if you subscribe to MS's Rate Alert free email newsletter Brigitte, but they actually covered this just last week! Lloyds TSB now have a cheque clearing system so customers can draw out cash from their account on the same day they pay the money in by cheque - that is cheques up to £1,000. They also offer immediate interest. Barclays do the same but pays interest after three days.
The Lloyds deal is causing a bit of controversy though because it doesn't include basic bank accounts, ie those aimed at low-earners. So if you consider making the switch make sure its applicable for you.