Can I use lpc2148 to host USB to connect two mass storage devices to facilitate transfer of data between them?
You might consider looking at newer LPC23xx, LPC24xx or maybe the even newer Cortex-M3 series LPC17xx.
Some of the chips in these familes have USB Host and/or USB OTG that can connect to a USB Device.
The OTG (On-The-Go) port can be either host or device.