MetroPCS is putting their agreement with CricKet into effect...now. You still can't call MetroPCS's coverage monolithic by any stretch, but they now have "300 cities" covered either directly or via free roaming on CricKet's network. The downside: you need a $45 or $50 per month plan to take advantage of this additional roaming, and the only things you'll be able to do are talk and text...but they'll both be unlimited. Also, if you're in Texas, between MetroPCS and CricKet a large portion of the state is covered, albeit with a lot of AWS towers so make sure you have a newer, AWS-equipped phone or you won't get the best coverage.
Speaking of unlimited text, if you have unlimited text messaging on your metroPCS plan within their (and now CricKet's) coverage areas, ou can now send and receive an unlimited number of text messages, even while roaming, at no additional charge. Voice minutes are still either 49 or 79 cents each, however, and rome roaming carriers don't support text messaging, though that number is decreasing to near nil now.
The limited nature of the CricKet roaming agreement is disappointing, but unlimited voice and text in an expanded area, mated with unlimited text messaging practically everywhere, is a very, very nice upgrade for MetroPCS.