Can your scouts have more than one assignment at the same time?

And if so, how many can they have?

as far as i know they can have as many as you choose to give them but they wont have much time to complete each assignment if you give them to many.

You can assign them to scout:

1. next opossition and one region/nation or,

2. one competition (reserves-under 18s-European championship etc.) and one nation/region, at a time.

I regularly assign a scout scouting eg Italy to give me a report on a player playing in Italy. I mean a scout can be scouting a country/region generally, and scout specific players (any amount). I also assign one to give me regular feedback on my loanees.

Unless scouting has changed significantly (other than being able to roam the world at their own discretion) since FM08 (I've only played a few game months of FM09 and am only able to scout my own nation anyway) you can give a scout as many nation/region assignments as you want. They can only scout one competition at a time, but any number of regions can be added to their list. They simply take them in order and when one search finishes they begin the next.

I don't know how the time taken is affected by you having them scout a competition as well though, esp. if they are scouting South America and e.g. the Championship in England. If they have to keep flying back and forth it ought to cost a lot (I dunno how much scouting aspects cost) and take much longer to complete the South American scouting mission.