Expect a new beta of MacJournal 3.1 in the next day or two. I rewrote a lot of the Blogger networking to avoid an issue that I see in the OS and hopefully it should never lock up the app ever again. There's also some other good stuff in there that I'd like to get out while waiting for the last two localizations to come back.
Tiger was announced yesterday over on Apple's site, and while I obviously can't talk about it a whole lot until it is released (those pesky developer NDAs) but rest assured that MacJournal works just fine on Tiger, both 3.x and 2.6.x. I'm not sure about 2.5.x, but you should be using 2.6 anyway. ☺ More details on this when Tiger ships on the 29th.