Technically, this is just an "image," not as in 画像 but as in a "mental image of what it might look like." It could actually be something cool, like a widget styled after a physical suica card. (Note that the app appears to be alpha, i.e. "ver. 4a")
This PDF and a FAQ on the mobile Suica site (both Japanese) have more details.
- On Saturday 7/23, service will begin at 4:00 for Docomo, 12:00 for AU, and 16:00 for Softbank. (No mention of Emobile)
- Support for commuter passes of various types
- Purchase of express tickets "green car" premium seat tickets
- Net shopping payments
- View Card autocharge
- A fugly widget
- Express reservations (EX-IC) in cooperation with JR Tokai (3-day advance Shinkansen reservation discount service)
- Suica charge from a bank account (details not yet available)
(See this post for a list of Docomo phones that have support). In late June, JR East will release more details regarding specific phone models that are officially supported. I don't know why the carrier matters, by the way. It would seem to me that if 1) the hardware supports it, 2) you have a mobile suica account, and 3) installed the app, it should work. Apparently this is not the case, though.
No news on a pasmo app for Tokyo subways and private lines. A feature phone mobile pasmo app does not exist.