No it can't.
The mirrored database remains in a state of "restoring" until it is brought into service through either an automatic or a manual failover from the principle database. The database is unusable while it is in a restoring state.
You can take snapshots of a mirror database and then restore these onto a live reporting database (although not if you are using sql2008 as your mirror database according to this article) however this could be processor and hard-drive intensive. It would also mean your reporting would not be live. If this was not a problem then you could automate a snapshot from the mirror database onto your reporting database nightly for example.
We are also looking to seperate our "functional" database activity from our "reporting" database activity. Instead of taking the snapshot approach we are looking to use database replication so we will have a live copy of our database which we can use for reporting.