Anyone know if the monorail is up and running yet? thanks

Yes it is

I was there last week--didn't take it but was told it was operating

The monorail has been up & running since about Christmas and as far as I know there have been no more problems with it. It sure is a cool alternative to either walking or driving along the Strip.

I'd heard that for 2 or more people, a taxi is actually cheaper to most locations.

Whether a taxi is cheaper or not would depend on where you're going & from where - many of the taxi drivers around here go the long way around if they get the chance and then the meter keeps rolling. If you're staying on the Strip - or at the Hilton where there's a stop, and intend to go back and forth a lot, then it's good to get the daily pass - one time fee and you can go on it as many times as you want. Otherwise, taxis might be cheaper, it's really very dependent on what you want to do and your location & destination. At least now you have another option.

24-hr monorail unlimited rides pass is $10 (no tips

The route and stops don't look too convenient looking at the website map, but I am determined to try it at least once (yeah, I know, such a strange definition of "fun") and let you know. I'll be there Feb 20-25.

FainaAgain - the stops aren't bad on the monorail. We had a room at Paris and walked through the connector to Bally's and then out past the pool. The stops are all located in the back of the hotels since that's where it runs - along the backside of those hotels so don't expect much of a scenic view unless you consider apartments, etc scenic. The Hilton stop comes out by the Star Trec bar which is pretty convenient. It's a fun way to get around and very convenient in that they run - each direction - every 10 or 15 minutes. And, like you pointed out - a $10 pass gives you unlimited use for 24 hours and you don't have to tip or endure scary taxi rides!

do they still have the free monorail from MGM to Ballys and from Monte Carlo to Bellagio?

The old MGM-Bally's monorail was incorporated into the Las Vegas Monorail. You can still take the monorail from MGM-Bally's but now you have to pay since it is part of the Las Vegas Monorail.