Over at the Standard, Marty G posts in praise of Red Alert (the Labour caucus blog). And I have to agree. It's a fantastic tool for connecting MPs with the online and getting them to front up and explain themselves. It's also great for showing us parts of Parliamentary business - such as select committee hearings, written questions and overseas trips - that we don't normally see. And they clearly listen to the feedback - there have been Parliamentary questions asked based on material in the comments. Though sadly, this isn't true in every case.
The Greens have been doing this for ages at Frogblog, and an increasing number of their MPs are posting to it, but its still a party blog rather than the individual voices of their MPs, and it has a different focus - more on the issues, less on the day to day work. And there seems to be less direct feedback between the MPs and the readers (though given the colonisation of Frogblog's comments by hecklers from the sewer, that's hardly surprising).
It's a fantastic experiment in direct communication between a caucus and its political activists, and IMHO a massive success. Every party should have one.