The BBC has reported on its site that more postal voting trials are 'possible' according to Local Government minister Nick Raynsford MP. The BBC article is essentially following up responses to a House of Commons report on the pilots.
The snappily titled 'Office of the Deputy Prime Minister: Housing, Planning, Local Government and the Regions Committee' published their seventh report specifically on the matter of all-postal votes. It's a good report which makes excellent recommendations to improve the security of postal ballots. In particular the report recommends the voter registration is tied to the individual and not the household in future. This would allow a pass code to be written onto identity slips and checked electronically during counting.
They also recognise the pressure for postal voting is due to desires to boost turnout. Yet they conclude that 'the Government must not rely on changes in the electoral system to increase voter turnout, they must also ensure engagement of electors in politics.' Good stuff.