If you set it to 0.0 on a spy that is cloaked, he will become uncloaked. If you set it larger, the spy will remain cloaked for a longer period of time. THe number also shows up as the number of bars in the spy's wristwatch/cloak meter.
There are also bits in m_nPlayerCond
Code:
FindSendPropInfo("CTFPlayer","m_nPlayerCond");
that relate to cloaking and uber,etc.
if m_nPlayerCond & 32 then the player is ubered.
if m_nPlayerCond & 16 then the spy is cloaked.
if m_nPlayerCond & 8 then the spy is disguised.
if m_nPlayerCond & 1 then the player is slowed (sniper is zoomed or heavy is firing or spinning his barrel)
Turning off bit 16 will uncloak a spy.
Turning off bit 8 will un-disguise him.