The UMPC market has been quiet for a while, with netbooks and smartphones narrowing the niche (which was small to begin with). However, Viliv seems to have hit a home run with the S5. This is about as good as you can do with a 4.8" screen and Windows XP. Battery life isn't bad (Chippy at UMPCportal says 6.5 hours, see
Viliv S5 UMPC. Detailed First impressions), and 200 hours in standby mode helps.
jkOnTheRun also has a review,
First Impressions of the Viliv S5 Premium UMPC, which includes using eReader for ebooks. Since this is running Windows XP, many readers are available (not all with work on a small screen, but the resolution is 1024x600 just like some netbooks).
The first shipment to the US will only be 200 units, which
Dynamism will be selling for $599 (with some bonus extras). It will be coming to Europe with a 3G option.