As often happens, the last 6-12 months have seen a wave of new companies providing the same type of service - in this case online financial management. Basically Quicken/MS Money on the web. The best known ones are Mint and Wesabe, but there are others like Geezeo and Expensr.
First of all, I think its an area that was begging to be put on the web. After years of using MS Money in fits and starts and never being completely satisfied with the experience, I now find myself a satisfied Mint user and getting more out of it than I ever got out of Money.
But the interesting point for now is around the different routes Mint and Wesabe have taken over the last few months and the apparent results (of course, its still very early and things could change). I've used both of them and I have taken two lessons out of seeing their development:
1) Good UX trumps privacy concerns (within reason) - I started using Wesabe early on and had a reasonably good experience. But the fact that they wouldn't directly connect to banks to get transaction information always seemed like an unnecessary inconvenience - they had all my transaction info anyway and, while it not being able to connect directly to the bank should make me feel safer, the reality is that I am not concerned (I would catch fraudulent transactions and most banks would let you off the hook if notified quickly enough). Mint, on the other hand, from the beginning connected directly to banks, making usage simpler and more streamlined. Interestingly, and belatedly, Wesabe just announced direct upload of transactions from banks.
This wasn't the only reason I switched though. In fact, I gave Mint a try when it opened up to the public, didn't like it and stayed with Wesabe. However this brings me to the next point.
2) Rapid improvement/iteration is (obviously) a must - As mentioned above, I initially tried Mint, didn't like it enough to switch and stayed with Wesabe. However several months passed and I noticed very little improvement in Wesabe - tagging was still flaky/annoying, there was no way to easily track spend across categories/time, etc. Early this year I logged back into Mint for the heck of it and was actually blown away - the things I remembered as annoying/lacking were gone. And I found that it had features (like the Trends tab) that blew away anything Wesabe had. So I have now fully switched to Mint and am a happy user - its a really good service (with a few minor annoyances).
Based on conversations and imperfect stats, it seems that Mint is clearly the leader in usage now. I attribute this lead to the two points above. For 1), the fact is that privacy, in my opinion, is just not that big a deal anymore. As long as the company is not a fly-by-night outfit and has reasonable safeguards, I think most people are over, or soon will be, their privacy concerns. Scott McNealy had it right 9 years ago. Point 2) is just common sense.
As a final note, I haven't used any of the other services out there. If anyone thinks they are better than Mint, I'd love to hear about it. Of course, one of the great (for the providers) and scary (for users) things about these services is that they are very, very sticky. I have so much data in there already that an alternative would have to be A LOT better for me to consider switching.