Spam conundrum

Why is it that this blog, which has been online for, what, less than a month? has already had its first piece of spam caught by Akismet, while my other blog,* which has been up for three years and was on WordPress 1.5 until just two months ago, hasn’t gotten any?

*Sorry, no link – it’s a family group blog and we’re all posting under our first names only to preserve privacy.  If you know me in real life, you probably know what it is, and if not, ask me and I’ll give you the link.