I love apps, I really do. Windows Phone recently passed the 50,000 apps mark, and there will be an app marketplace built into Windows 8 as well. I recently interviewed the guys from Anlock, who talked about what a boon marketplaces are for startups, and I suspect I’ll be talking to more app developers in the same vein.

Then in late December, ESPN updated their mobile website. If you have a relatively current smartphone, go visit it now. It’s simply amazing. ESPN has a Windows Phone 7 app, but I see no need to install it now. I have the website pinned to my start menu, and I visit it quite frequently to read stories and check stores. It’s very app-like – it has nice big, touchable links that feel like buttons. It just works. An native app might be able to improve the experience slightly but not by much.

Clearly HTML5 and the rise of good browsers on smart phones enables this kind of experience. What does it mean for startups? When will you favor a mobile website instead of building an app? When will you favor apps?