I think the layout similarity was an issue; but it seems to me that they just have demonstrated a barrier to entry (a non-product one).
For a product company, 37Signals does a lot of blogging, conferences, a book and so on. I think the guys are good at this, and they really enjoy it. It makes me think that, in a way, 37SIgnals is really an educational/PR company, that happens to make money from their software. If you want something like what they make, you'll need to pay someone to host it - why not them, since they are nice guys?
For a product company, 37Signals does a lot of blogging, conferences, a book and so on. I think the guys are good at this, and they really enjoy it. It makes me think that, in a way, 37SIgnals is really an educational/PR company, that happens to make money from their software. If you want something like what they make, you'll need to pay someone to host it - why not them, since they are nice guys?