I have experimented at various times with both Tumblr and Posterous which are hosted blog services. I tend to view them as useful services for a scrapbook style blog, a linkblog, a lifestream or even a fully fledged blog. If I was starting a blog today, I would probably use one or the other.

Posterous, in particular, has been getting a lot of coverage recently and I like the ease of use, the ‘Post by Email’ facility and continue to follow developments with interest.

I often describe Posterous as a ‘blog for people who don’t want a blog’. For example, Uncle Harry doesn’t even know what a blog is and certainly doesn’t need a blog. However, Uncle Harry is also perfectly capable of attaching photos of his sailing holiday in Greece and emailing them to his daughter, brother, wife, friends and colleagues. He could do this using Posterous and, lo and behold, without even knowing it, he now has a blog.

Posterous is a hosted blog service and until recently, was limited to a single, universal theme. This didn’t particularly bother me as I quite liked the plain, minimal looking Posterous design.

I also felt the default Posterous theme actually helped to reinforce the Posterous ‘brand’. Whenever you encountered a Posterous blog, you could immediately recognise it as such.

However, custom themes were a frequently requested enhancement by (potential) users so Posterous have finally added support for your own themes including pre-built designs, custom header images, full HTML customisation and interestingly, the use of Tumblr themes.

Now I suspect that supporting ‘Tumblr’ style themes out of the box was a master stroke. Posterous users immediately have a wealth of pre-built, attractive looking themes available off the shelf, free of charge.

Tumblr have even helpfully created a theme repository for Posterous users. You just find a Tumblr theme you like, copy and paste the HTML, dump it into Posterous and you’re done.

You now have a lovely, stylish professional looking Posterous blog that looks identical to a lovely, stylish professional looking Tumblr blog.

I love the way TechCrunch uses the the term ’leverage’ to describe the addition of this (almost seamless - some blocks are not supported) integration with the Tumblr theme engine.

Of course, all themes are just HTML and CSS but I can’t help wondering whether the Tumblr development team and their own band of loyal and passionate users feel quite the same way about this wonderful, new addition from Posterous.