Connecting two Ethernet PHY without magnetics?
You might be interested by these Application Notes about transformerless/magnetic-less ethernet application
Intel AP-438 : http://www.intel.com/content/dam/doc/application-note/8255x-fast-ethernet-controllers-without-magnetics-appl-note.pdf
TI AN-1519 : http://www.ti.com/lit/an/snla088a/snla088a.pdf
They both have an example of transformerless operation on a PCB, with a capacitor in place of a transformer. In a case where you control both side of the connector, only one capacitor on the line can be mounted. But if you control only one side you have to put a capacitor two, in case the other side has nothing or has a transformer.
I had to work on a 1000Base-KX backplane connection, and its problem is this standard is not very well known and you can have difficulties to implement it, have information about it, etc.
In my case I needed to have an oscilloscope pattern to observe the signal. After few email to the oscilloscope company and few phone calls I had them understood that I was talking about 1000Base-KX and not 1000Base-CX (Ethernet over Coax).
The 1000Base-KX was "retro-implemented" in the IEEE802.3 when the 10GBase-KX was created. So the 1000Base-KX is a standard derived from 10G and officially become a IEEE standard years after the adoption of the Gigabit standards.
Also 1000Base-KX only need 2 pairs (Full-Duplex) but the operating frequency is around 1Ghz which involves signal integrity issues where 1000Base-T and 100Base-T(X) stays at 125MHz.
What you really need is a different variety of PHY, so called "backplane phy". Those are specifically designed to work with capacitive coupling over PCB traces.
The relevant standard is called 802.3ap. Here's a nice overview: ftp://ftp.t10.org/t10/document.05/05-214r1.pdf
Many modern PHYs can be put into a 1000Base-KX mode through a bit of configuration tweaking.
One long running and popular PHY of the above variety, which can be frequently found on all kinds of expansion boards is Marvel 88E1145: http://www.marvell.com/transceivers/assets/Marvell-Alaska-Quad-88E1141-45-GbE.pdf
Many integrated Ethernet controllers also support this mode of operation (Intel as an example): http://www.intel.com/content/dam/doc/application-note/82545-82546-82571-82572-631xesb-632xesb-gbe-controllers-serdes-design-appl-note.pdf
The transformers are there to help impedance match to an RJ45 Ethernet line so if you're confident that the impedance match you will be fine even for tens of feet.
Small print
Transformers also protect silicon from line disturbances that might otherwise kill silicon so be aware of this. They also isolate galvanically the two systems and stop earth loops passing currents that can cause poor data quality. Providing you don't need to have a dc level on the connection (that is usually harnessed via a transformer centre-tap) and you have both systems connected thru capacitors it should work. Read the datasheet.