How real is Gordon Brown's bounce?

One of my favorite sites is politicalbetting.com, mostly written by Mike Smithson.

Today Mike has this article delving deeper into the poll numbers that give us the Brown bounce.

Although once weighted, there is a bounce, there are some oddities in the unweighted numbers, in particular more people saying they voted Conservative in 2005 and less saying they voted Labour, which is causing the shift.

As Mark Senior points out in this comment here, we are also not seeing any bounce at all in real elections, that is council by elections.

In fact the local by-election results over the last month seem to still show a Conservative lead of something like 8%.Now that will not actually translate into a general election lead of 8% but you would expect it to have been dented by a Brown bounce if it is as big as some of the polls say.