I'd advise anyone who is concerned about stability to avoid Wine for now. Last time I looked, the website was full of warnings about Wine's experimental nature. I would take those warnings very seriously. There are also performance issues. If you're looking for something to play around with, Wine's fine. If you're looking for something to get real work done with, I'd avoid it.
Probably sound advice, but maybe some aren't quite that cautious. I run Lotus Notes 5 under Wine (an April snapshot) and it works just about perfectly. My current process has been running 6 days (which is an achievement for Notes under Windows, let alone Wine!) and it's not so much as hiccupped. I don't think Wine will ever be a serious contender for selling cross platform software, but it is up to "getting real work done", at least in some circumstances.