Hrm...

Here's the data sheet:
http://www.cisco.com/en/US/products/hw/modules...heet09186a008014cb5e.html

I don't see anything about a minimum distance...

I do remember when I was in school one of my instructors was trying to get a 1000base-something to work, but was having all kinds of trouble (it was fiber, I know that for sure).

In the end he had to back the connectors out of the socket a tad to weaken the signal strength as it was too strong for the receiving end. It was a very short run (6 feet-ish I think)

EDIT:

Oh, there it is. It is on that page I linked to:

Quote:
Table 1 provides cabling specifications for the Cisco GBICs that you install in the Gigabit Ethernet port. Note that all Cisco GBICs have SC-type connectors, and the minimum cable distance for all GBICs listed (multimode fiber [MMF] and single-mode fiber [SMF]) is 6.5 feet (2 m).