Today I received a letter from Google Maps API Developer Relations about the end of the maintenance period for version 2 of the Google Maps API.
Under the cut - translation and reflection

We are contacting you because your email address associated with the Google Maps JavaScript API v2 key is used for the following domains:
°% domain_name%
As you should know, the three-year obsolescence period for version 2 of the Maps JavaScript API ends in May 2013. After this date, the API will no longer be supported, and functions may not function as expected. At some point, your cards on V2 may stop working completely.
The good news is that Google Maps Javascript API v3 is more reliable and has more functionality than v2, and for the vast majority of sites there are no problems with migration to V3. Therefore, we strongly recommend that you review our migration guidelines, and strive to migrate until May 2013.
Of course, for most sites that use only a couple of markers and a map, the problem with migration is only to read a small manual and change a couple dozen lines of code.
As for sites that use google api for placing multiple markers and having a wide functionality of working with a map, this will be a big problem.
As my experience shows, such sites were written for a long time, and this is a big problem. Rewriting such a site I spent more than a month just to understand how it functions. The absence of the architecture itself, php classes, the use of frameworks, a hash of html + php + javascript in one file are only flowers. The berries were in the use of old unused libraries for 5–7 years, and, of course, “Easter eggs” in the form of directly executed code in the middle of functions.php.
As a result, we had to rewrite the entire functionality of the card and match it with the rest of the old code.
I want to advise site owners on V2 not to delay the migration to V3, since moving to V3 can be a long and painful process.
After all, no one wants to, at one point, the site just stopped working.