David Cameron has decided to attack the Liberal Democrats, currently resurgent in opinion polls (see here for various relevant posts) on the basis that a vote for them would bring back the old politics of a hung parliament.
The first thing that's worth pointing out is that if the electorate decide that the Liberal Democrats have a serious chance of forming a government, it is quite possible that they will do so outright. Part of the reason that people have historically been reluctant to vote for this party is because, in a "blue/red" world, it can be regarded as a wasted vote. The last few elections have seen this gradually changing - the LibDems look a lot more viable as a mainstream political party starting from a baseline of 60 seats than they did in 1992, with 22 seats.
In any case, I have to say that the idea of a hung parliament doesn't exactly fill me with dread. The "non-hung" parliaments we have seen since - well, let's say 1979 - have resulted in conservative political ideology eroding societal structures, and then labour political ideology increasing the size of government (and corresponding tax bills) like topsy. Assuming it is possible to form a government, a term of politics based on something approaching consensus, and with at least a large minority committed to probity in public life, sounds like a very nice idea, thankyou. I suspect that in the event of a hung parliament, Gordon Brown would thank his lucky stars and be prepared to sacrifice a great deal of the Labour agenda to have a crack at remaining Prime Minister. And after the election campaign has highlighted the flimsiness of the Conservative party, I suspect that when push comes to shove, Cameron would also think that a hung parliament would be a much better outcome than what he really fears, which is the Liberal Democrats becoming a genuine third party, the political equals of Labour and the Conservatives.