Euribor is the interbank offered rate and it may vary from the ECB as it is based on an average of overnight interbank lending rates.
There is a lot of mis-information going through this thread. First of all Euribor is an official fixing rate set each day at 11am CET for a variety of lending maturities - from overnight (Eonia) out to 1 year. The rates are to be found here
http://www.euribor.org/html/content/euribor_data.html
There has been comment that they are used in the derivatives market - yes in so far as they are used as the floating index rate for a variety of derivative instruments such as interest rate swaps.
It is true that Euribor rates change each day, so you cannot compare like for like with ECB rate, they are of course an indicator of what the market thinks is the direction that ECB rate is heading to.
The OP's friend has not indicated what Euribor they have been quoted. However, as you can see from the 2007 data file on the above link page, the 1 week Euribor is 3.85, whereas the 12month is 4.40. A difference of 55bps. The Euribor maturity is effectively like a mini fixed rate for that period. If you are borrowing for say 5 years on 12 month Euribor, there are 4 resets of rates plus the current rate for example.
As you can see, the Euribor rate is price sensitive to the day's market - whereas the ECB rate is fixed until the next meeting.
Borrowing on Euribor usually gives better pricing as the Bank can hedge the risk easier in the market than ECB repo rate as there is no derivative market in ECB repo rate.