According to RustyBrick, the iPhone Siddur has:
- Weekday prayer texts with easy and quick navigation
- Nussach for Ashkenaz, Sfrard and Sefarad Mizrachi
- Zmanim Calculator based on your location (with override)
- Minyanim database (finds the nearest shul to your location)
- Luach or Jewish Calendar
And there are more features to come, including:
- Mizrach Compass
- Smart Siddur (will show you the prayers you need only for that day)
- Remember last location in Siddur text
- Siddur bookmarks
- Chabad Nusach
Before the iPhone Siddur, there was iDaven, which could be downloaded onto an iPod or phones like Treo, Blackberry and Sidekick. But compared to the iPhone and its ability pinpointing davening times and finding nearby shuls, the iPod feels soooo last year.
Photo by rustybrick.