Clearwire, Sprint and a part of a group of operators and vendors that have asked the 3GPP standards body to start work on specs that would allow TD-LTE to be deployed in the US in the 2.6GHz spectrum — which is now used for mobile WiMAX in the U.S. The proposal has been accepted by the 3GPP just as TD-LTE has begun heating up around the world. 

Part of the 2.6GHz band is already specified for TDD, namely the 2570MHz-to-2620MHz band. The new work at the 3GPP will ensure that all of Clearwire's spectrum will have a definition for TD-LTE operation and will get the TD-LTE specs in line with Federal Communications Commission (FCC) requirements as well.

The specifications for the US 2.6GHz band for TD-LTE is scheduled to be completed by March 2011.

Qualcomm recently announced its bid in India's wireless broadband spectrum auction to promote the TDD (time division duplex) version of LTE, known as TD-LTE,in the 2.3GHz band.

For more see this Light Reading Mobile article

Further, In response to a question about harmonization of LTE and WiMAX by Michelle Donegan at Light Reading, LTE Watch posted the following:

In my personal view, the chance of LTE and WiMAX being merged even in the future is slim. Technically, even though there are many commonalities between the two standards (OFDM, MIMO, all-IP architecture, etc.), the details, especially at the Physical Layer-level, are pretty divergent (ex. LTE uses SC-FDMA for uplink whereas WiMAX ODFMA). A harmonization may happen in the network level for seamless handover between the two networks but it's pretty much a dual mode type of service just done in a more efficient way. From this perspective, in order for a complete harmonization to happen, one camp pretty much has to ditch their previous developments, which seems unlikely. From a political/market perspective, almost all major players in LTE are not active participants of WiMAX (Samsung is an exception), so there is usually some resistance towards WiMAX from the LTE camp. I think VZW CTO's comment during the recent CTIA Wireless 2010 in response to Sprint and Clearwire's call for LTE/WiMAX union (Clearwire CEO mentions that WiMAX could join LTE as one, Verizon Wireless CTO says no way) is somewhat telling of this sentiment. - Hyung