Alternative

Have a look for the TP-LINK TL-MR11U. Does the same kind of thing but has an additional USB port which can be used with a 3G dongle to share that over wireless. It has a 2200mAh battery, enough to run the wireless for 3 or 4 hours heavy use, which can also be used to recharge your mobile phone if you're caught short out and about! Only problem is that it seems to be China only atm. The configuration screens take a bit of working out but there's enough english in the page title/screen that you can do everything required. £22 from one of the Beijing uber-markets. Also supported on OpenWRT if you're feeling hardcore ;)