Working with TideSDK is quite easy. We are working to make the experience great for developers. You are essentially just creating an HTML5 app in a special Resources folder. In most cases you can drop an HTML5 app directly into the Resources folder, point to the index.html using TideSDK's configuration and have it running in minutes. TideSDK can be used to run clients, servers, processes, and workers. I tend to work with frameworks such as backbone.js where routing is baked into a single page app.
At the core of TideSDK is WebKit, the core technology that powers the Safari and Chrome web browsers. We use three different ports of WebKit in TideSDK, one to reach each platform (Windows, Mac, Linux). On OSX, we can also use the native WebKit. The APIs of TideSDK provide native UI capabilities (that we are enhancing over time). These include native windows, system trays, menus, and dialogs. You can also interact with the clipboard. We have networking and database capabilities, system notifications, and more. We patch Webkit to allow the interpretation of python, php or ruby in the DOM in script tags and are able to bridge objects between languages. Our API's really allow your to reach the resources of your system including interacting with its filesystem.
It would be fun to run meteor in TideSDK. It is currently possible to run node.js within TideSDK using an appropriate startup process so I cannot see an issue running meteor so that it can run client and server within an app.
If you need your apps to reach Apple's AppStore, TideSDK is the only framework that I am aware of that has this potential. Competitive frameworks use ports of WebKit that are not native to the Mac such as the Chrome port (appjs) or the QT port (Sencha Ion). Apple's scan of an app based on these ports will reveal the use of "private APIs". Therefore, you would could not enter the AppStore marketplace with an app based on these. TideSDK is different and can use the native WebKit implementation on OSX. More about this capability will be revealed in the upcoming TideSDK-1.4.0 release. Our upgraded WebKit will also bring the HTML5 capabilities right up to date with the trunk of WebKit. Many of our users are waiting for this important update.
With WebKit eliminated as a barrier to the AppStore, the last issue facing a developer is Apple's sandboxing and entitlement to the resources of the system. We are looking at possible solutions to aid developers with sandboxing requirements. Some apps will be suitable for sandboxing and others will not. That said, if your goal is AppStore compliance, you will need to work with restrictions Apple has in place. I hope this helps.