A recent Hacker News poll of OS used day-to-day, Linux finished second in frequency behind Mac OS: http://news.ycombinator.com/item?id=687267 . People who do dev/database/IT work frequently need snippets of text like IP addresses and passwords and API keys and this sort of tool would come in handy for us. But a lot of us run Linux as well. Even ignoring the nerd market, Linux is increasingly run by regular people on their netbooks.
I guess the reason I don't get this is that tech savvy folks seem like a great market to go after with your software, as they tend to be very influential in their social networks' decisions as well.
Apples and Oranges, I know, but I use and love Dropbox in large part because it works with 2 of my 3 computers. On the other hand, Evernote runs poorly on my mac and can only be accessed via the web on the others. I actually use dropbox now as I would evernote, by keeping .txt files in my dropbox.