Good question. You can bury the wire. Or you can buy the ones used for the lawnbotts. Lawnbott pegs are $40 for 200 at http://lawnbotts.com/accessories1.html
Some people use metal tent stakes, but I don't know if metal is good long term wise. Speaking of which, I'm not sure what material the lawnbot pegs are. I always use the ones from friendly because they're tough/flex plastic and hard to break.
I went to Menards and bought sod staples...they seem to do a real good job and are on sale at 50 for $3.50. Again they are metal, about 3-4 inches long. I used these for my invisible dog fence as well...they did the trick.
farmer, I think the metal stakes may be why your Evolution went out the boundaries. We recommend to use plastic for the Lawnbott. I haven't test this personally, but I've heard that metal stakes may pose a problem.
Good point - I am monitoring this...the out of bounds happened only once so far - without clipping the wire - I will keep an eye on it and up date this log.
I have been watching my lawnbott Sparky and how he deals with the metal sod staples which hold the perimeter wire down...have not had any problems with his operation due to the metal sod staples...
We use the metal lawn staples and they have worked fine. We did have an issue with zone-jumping, but it was because we have two zones with parallel sides. The signals from the two unconnected wires were interferring with each other, and it had nothing to do with the metal pegs. I haven't seen any zone-jumping since I figured out that I need to turn off the back zone while the Robomow is in the front zone.