On MarsEdit and iWeb
Superficially they sound similar: both allow you to edit weblogs. But beyond that simple sentence they’re completely different in intent.
Though I haven’t looked into iWeb’s features in any depth, it appears that it creates weblog pages and uploads them to .Mac. (It may also have an export-to-file-system feature where you can manually upload to other servers too, though I’m not positive of that.)
MarsEdit, on the other hand, is an editor solely. It works with weblog systems like Blogger, TypePad, WordPress, Conversant, and others. It doesn’t actually create weblog pages—that’s not what it’s for. Those weblog systems generate the pages.
(Note that ecto has the same intent as MarsEdit, and thus also doesn’t compete with iWeb.)
iWeb competes with Sandvox, of course, though I have hopes that Sandvox will still do well, especially as it’s not tied to .Mac but works with a variety of servers.
As a weblog generator, iWeb competes with apps like Blogger, TypePad, etc.—all those apps that MarsEdit works with. It also competes with other desktop weblog generator tools such as iBlog and Tangelo.
Just for jazz, to make things clear... there are several aspects to a weblog:
1. Editing interface.
2. Weblog-page creation.
3. Weblog-page serving.
So a workflow that uses MarsEdit might look like this:
1. MarsEdit for editing.
2. WordPress for page creation.
3. Apache plus PHP for page serving.
A workflow that uses iWeb looks like this:
1. iWeb for editing.
2. iWeb for page creation.
3. .Mac for page serving.
MarsEdit only ever does 1, while a big part of iWeb is 2.
It’s worth noting that MarsEdit works with the existing weblog ecosystem and iWeb is part of a top-to-bottom Apple solution. It would be easy to say something negative about how big companies want to lock you into their stuff at every step—but I don’t hang with that, at least not in this case. I like the fact that Apple does a top-to-bottom Apple solution—it leaves open opportunities for developers, which is a Good Thing.
(And, at the same time, it’s also worth noting that iWeb generates RSS, and Steve Jobs in his keynote made the point a couple times that Apple-generated RSS works with whatever RSS reader you have. So it’s not as if iWeb completely ignores the rest of weblog ecosystem: there’s no Apple-only syndication format, for instance.)
To sum up...
iWeb cool. MarsEdit cool. Not competitors.