The FCC website just posted a phone cleared for sale with WiMAX (Sprint's 4G). This new devices has the model number of PG06100, which is very similar to the EVO 4G's PG36100.
HTC just trademarked the name EVO Shift 4G, which many people speculate is going to be a Sprint version of the Desire Z or T-Mobile G2 but with HTC's Sense UI. I imagine it will not have the special Z-hinge of the G2/Desire Z, but will basically be a slider version of the EVO, although with a smaller screen.
Interestingly enough, some of the documents date to September 20, which is a real long time for FCC testing, and it might be launching eminently.