Good article from Clickz about rising pay per click costs.
No doubt the legal arena still has a lot of room for growth in the pay per click market and I expect many new law firms to get involved in the ongoing bidding war.
So costs will probably rise for many popular keywords over time, but its important to stay on top of the bidding and make sure that your covering all the possible keywords. There are many good values out there for keywords if you do the research.