TI will be introducing a new family of ARM based TMS570 devices later this year that will feature integrated 10/100 Ethernet. These devices will feature similar architecture and peripherials as the current TMS570 and TMS470/TMS470M devices. Please check the TMS570 web site (www.ti.com/tms570) later this year for more information.
I currently use the W5100 WIZnet etherent controller with the TMS470R1B1M. That's an option if you need to use the TMS470 series. It allows you to use SPI or general I/O ports to communicate and seems to be very reliable. Also, it has a hardware TCP/IP stack which greatly simplifies your usage of it.