How trendy are Christmas?

Blogpulse is webservice which could measure frekquence or popularity of different discussed topics on blogs. The searching is based on fulltext. That means that it show all texts which mention the searched word, but without any context and any evaluation. The nice example are Christmas. My hypothesis was that there will be nothing interesting about this topic at least during the summer months. I suppossed that there will be slowly increase during september, because Christmas time is comming. But as you can see in the graf, there was rapidly increase of this topic in blog´s articles during the end of June. It was very surprising for me...
After deeper scan of these blog´s articles I found out, that someone created and sent kind of enquiry regarding to books. A lot of people rewrote the list of books and added marks about quality and readability ect. and presented it on their blogs.
And how could it influence the Christmas topic? Easily ... the first book in the list was Christmas Carol of Charles Dickens.

Conclusion
This kind of service is interesting, but actually it doesn´t tell us anything important about context, which is most important. Blogpulse is not the only service which you can use for such measuring. The similar service offer Google Trends. With small difference and that is that they are measure the popularity of keywords used in google search engine.