Google Nexus One will be updated soon with Froyo 2.2 that includes the WiFi hotspot.
I have the update on my n1 and it works great for tethering if you need to. The 3G model was all that was available at the store I got my ipad from. I couldn't wait so went ahead and got it. I will use the nexus 1 for a backup, so far I have been less than impressed with at& t's 3G.
If your budget will allow, i would go with any of your favorite phone not worrying about WiFi and get a MiFi from the same carrier. Most leading phone carriers will package both in one account and the monthly is really not that bad.