The manufacturers in question include Lenovo, Asustek and many others who are preparing to launch 22nm Ivy Bridge-based motherboards on Intel's upcoming Panther Point chipset (see: Intel 7-series chipsets). While Intel's current Thunderbolt spec for Sandy Bridge-based motherboards on the Cougar Point chipset (see: Intel 6-series) is based on copper cabling, manufacturers expect Intel will shift to optical cables for Ivy Bridge which will bring higher bandwidth and longer cable lengths.
Of course, DigiTimes is clear to note that Thunderbolt optical cables likely won't be adopted for Ivy Bridge-based motherboards until the end of 2012, meaning the first few months of initial products in Q2 and Q3 may feature conventional copper cabling.