"TCP/IP on 8052?" is usually one of those questions which comes up with tedious frequency, but I don't seem to have seen it for a while now. :-)

So here's a new answer to the old question:

www.OpenTCP.org

Although the publicity talks about a variety of 8/16-bit microcontrollers, the only one they actually mention on the site is the 16-bit Fujitsu MB90F553A.
System requirements on this target are here: basically ~18K code and 2.5K data - but on a different target (especially with a different word size) & different Compiler, who knows...??!

But there is a thread on their forum from someone doing it on an 8052 with Keil C51:
http://www.opentcp.org/phpBB2/viewtopic.php?t=4

Don't forget that "Open Source" does not mean that it is free of all restrictions - see the Licence Conditions