Which podcasts are in the top 10? That depends on whose list you’re looking at. In fact, among the services that keep track of such things (using whatever hinky methodology they may apply), there’s little in common. I know because I can look at all of the major top 10 lists in one place at a new service called Popcasts.

Popcasts is in beta (but then again, what isn’t?), but still offers a simple, clean interface for scanning the most popular podcasts. Sources include iTunes, Podcast Alley, Odeo, Podnova, Podfeed, iPodderX, Podcast Pickle and Podcasting News.

The site updates hourly and lets you subscribe to separate RSS feeds for each list. And in case you’re wondering, The Hobson & Holtz Report didn’t make any of ‘em.