I never got into Pownce, so its loss was no skin off my back, but I can see how its users could grow accustomed to doing more than Twitter's razor-thin feature set. Much like services including FriendFeed have grown their user base with a diversity of options, Schmownce shows some potential, especially when it comes to sharing messages with a small subset of your friends, with "groups", and seeing a reply stream in one place.
After being introduced to the service by Ajit D'Sa, who works for TRNSFR, the company behind Schmownce and other products, including TweetShrink, I checked out Schmownce, and found it to look like a quieter version of Twitter, but the major thing you'll note is instead of a simple "What are you doing?" prompt, you see a box with four options: "Message", "Link", "File" and "Event".
A message works like it does in Twitter. You write a note, without a 140 character limit, and send it, either to the general public, to an individual friend, or, in a new twist, to a group you may have created. Like in TweetDeck, you can select a subset of your followers and place them in a group, but unlike TweetDeck, you can actually message some of your followers, rather than the "blast all" option Twitter prefers.
A link adds a hyperlink to an external site. Adding a file, such as an image, either displays the graphic, or posts the file for follower's access. With a limit of 100 megabytes, that's fairly robust, though I didn't test it. You can also post an event, with a location and a date, though you can't pick an hour during the day, or a duration, so it's no replacement for Outlook - just a good way to let your followers know something's upcoming.
Unlike Twitter, Schmownce lets you have threaded replies, so I can reply to specific messages on any of my friends' accounts, see the total number of replies, and get e-mail notifications from said replies. Nothing tremendously Earth-shattering, but still... a potential future direction for Twitter, should it be interested.
Given the best benefits of Twitter are the vast community and its interlocking with developers on third-party services, Schmownce doesn't exactly have the Fail Whale provider shaking in its boots, but if you find these functions interesting and miss your Pownce, go check it out. As always, you can find me at: http://schmownce.com/louisgray.