Well, SL advertising isn't anything like Home's:
Home: On the wall, on the floor, on the clothes, on the bowling lane, on trophies, on your left pupil, etc. at all times.
SL: Click search, specifically search for said company (means you already need to be aware that it exists, go to company's land, wait 15 minutes for low quality "advertisements" to appear, and leave.
I don't think SL is supported as much by advertisements either, but more for the money $10,000 "Lindens" a month for a entire island (10,009 In-game Meters, IIRC), which they also get from any verified members who buy land, with the amounts varying depending on what size lot you have (minimum is usually 512 IGM).
From,
Chris.