Thank you for your interest Divesh,
Copied in part from my post to another thread......
Many people use mobile GIS in remote areas with no connectivity (geologists, foresters, biologists, etc.). This may be due to remoteness or overseas projects (most research budgets or companies will not cover the roaming costs; and access to map servers is blocked in some countries).
The standard right now is an HP Ipaq running ArcPad. It has been noted in reviews of the iPad 3GS that mapping is the future "killer app" for the iPad. The screen size, brightness, weight, native GPS and COST are all in the right range.
Ideally we need the ability to download proprietary base imagery and shapefiles onto an iPad from a PC, edit the shapefile in the field, and upload the shapefile back to a PC. You may not have connectivity at your hotel or basecamp so direct PC connectivity (cable or Bluetooth) is needed rather than a server-client model.