There are an increasing number of stories in the press regarding the way in which the Police, Community Support Officers and Private Security Guards are interpreting / enforcing Section 44.
In my opinion it appears that the situation is getting worse rather than better, even though Senior Police ranks are regularly sending out internal memo's to officers outlining what they can and cannot do under Section 44.
The first document I read on this was here and although this document is more to do with Photographers rights in general rather than S44, it is very useful and has been kept up to date by the site author.
There are now 1,000's of sites with horror stories from photographers both amateur and professional. Too many to list here and you only have to pick up today's newspaper or click on a news website to get to the latest ones.
That said, I do think that the Not a Crime group on Flickr is really good as well as the I'm a Photographer not a Terrorist website. They are also on Twitter (here) and Facebook (here) and provide links to all the latest stories.