Its a system function it came with the phone, it won't let you uninstall btw, you'd have to root your phone to uninstall it.
I don't remember getting an update for it...
As for what is causing the threat detection, not sure how true this is but this is what I found, thought I'd pass it along.
"AVG flagged your T-Mobile Android phone due to the Carrier IQ application calling itself System Manger app. Carrier IQ is a metric reporting data collector and basically infringes on the user privacy. Several Vendors (Verizon, AT&T, iPhone etc) have removed the Carrier IQ app due to invasion of the End User privacy.
The only way to remove the Carrier IQ so far is to "root" (jailbreak) the phone."
I'd take it with a dash of salt but seems like a valid reason, I'd rather ask AVG for confirmation however.