As I wrote in The perfect PDAsmartPHONE I bought a iPAQ h6315. This device is really great even it runs Pocket PC. Also the battery is not as bad as many websites report. I do use the wireless (802.11) often but it does not seam to eat the battery too quick. I now really enjoy VoIP with SIP and SJphone.
Also I want to mention the effort to port Linux to the h63xx has started at handhelds.org.