Numbers has a vlookup function, but it doesn't do what Excel's will do -- at least not with a simple spreadsheet I use at work all the time. Excel's vlookup will reference a worksheet in another file such that I can take a master parts list and/or price list and reference it in another sheet, such as a job estimate. If the master list changes, I change it in one place, reopen/refresh the estimate sheet and the data all changes appropriately.
I'm still very new with Numbers. I've been playing with it for only an hour. I don't know if the reusable table and template features in Numbers will do what I want, but the fact that I cannot take Excel workbooks containing Excel vlookup functions back and forth from work (Windows land) and home (Mac land) is a disappointment.
Numbers is one nifty piece of eye candy thus far, though.