In Windows Phone 7 there is a limit of max 10 side-loaded apps on developer unlocked device.
Is this limit still there in Windows Phone 8?
As andrewpey wrote the limit for normal accounts is still 10 apps.
It is also worth noting that for Student accounts (via Dreamspark) the limit is 3 side-loaded apps.
Yes, it's still limited to 10 apps, according to MSDN.